Lol...that is a heeler for you!
Maybe someone can do a DNA test on some of the chocolate and yellow/cream heelers to help determine if it is just a mutation in the breed.I wonder if they may already have done that though since I hear some ACD breeders who breed for conformity shows test for the e versus E and b versus B alleles mentioned. They look like working line ACDs to me, including the very clean mouth corners, and these are the sorts of dogs (body types) I am used to seeing on working ranches. They definitely are not from show lines though, and definitely would not do well in conformation showing. Aye, I've read that link before, and found it very interesting.
I'm not really sure why a chocolate dog would be surprising though? Just seems like it is a dilution of the black patches:
http://newacdgazette.com/2011/01/17/do-we-still-breed-the-right-colours/ (do a text search for "chocolate", cream is mentioned as well).
http://www.adcb.au.com/acdcoat3.htm (Chart breakdown specifically for ACDs if scroll down a bit. This one also mentions the black and white with no tan that was mentioned a bit earlier in the thread)
This seems to be similar to what happens in other breeds:
http://www.borzois.com/coat.color/brown.dilute.html
Chocolate ACD from purely working lines: http://www.bchfarms.com/siteimages/205_1138 Reba 2010 resized.JPG
No worries, you won't be seeing them in breeders geared for conformity showing. They are not to standard, and I seriously doubt that would change, and I personally have no desire to see that aspect change. But for someone like me looking for a good working dog from solid working lines, I'll take 'em in any color they come so long as they are hardy, balanced, smart as a whip, and of the less bulky head possibly older-styled build I like.
Here is Dolly and Hubby's bird dog Chase. they are such goofs!
Well except for in the breed history it specifically states the black and tan kelpie of the time was used. I still say these dogs ( the chocolates ) are coming out of heelers and not purebred ACD's and there is a difference. I don't want overly huge bulky dogs that can not work but I also don't want the weedy needle nosed dogs I see around here that are referred to as heelers. You have to remember these dogs can withstand a kick from a cow often to the head ( I have seen an ACD jump back up angry after this! ) so they need substance and bone but not so much that they would be slow. Most of the people I know with AC D's have been in it 20 -30 years, they want to preserve instinct but have also worked very hard on the temperament of this breed. My dogs are NOT shy, squirrely dogs that freak out when approached by strangers, they may be cautious but not fearful. This is what the responsible ACD breeders have been working towards as the original imports tended to be either aggressive or fearful. We also test for genetic defects, none of the heeler breeders I know of do this nor do they keep pedigree records most of the time. That is why I am SURE they probably have either infused other breeds like chocolate border collies or the chocolate kelpies at some point. Most of the dogs refered to as Heelers in this country were the descendants of the McNivens dogs that were never accepted into the AKC studbooks as their lineage was questionable.
The genetics on the various sites are more solid to me though than personal experiences from breeders, no matter how long they have been involved, or their caliber. This is particularly true for me because it isn't unheard of for variations to be denied from various breeders. Definitely personally seen some silent culling in the show (and heck, zoo!) world for other species. I imagine the black and tan kelpie would be carrying the same chocolate mutation as mentioned for various black and tan breeds. For me, the breed started way before the AKC standard, even a bit before: http://www.cattledog.com/standards/origstandard.html . My only real beef with the blockier dogs (show or work, though I've only seen them originating from show lines thus far) is that they are all I am finding lately, and are being bred into working lines. I feel that the dogs pictured at the beginning of the thread are more likely to be mistaken for a pit bull than a dingo, which is not a trend I saw in the past. So long as I can find dogs with the traits I personally want to see in cattle dogs, I'm happy. Really don't care if it is a 'heeler' or a registered conformity show ACD, if it is chocolate, an even blue, or purple (so long as the patterning the breed was founded on is present), so long as the dogs come from a solid line (no additions of border collies, aussies, and other common add-ins), and displays the traits that say "cattle dog" to me. If dogs like the ones I'm looking for die out, so do cattle dogs for me personally. 
I'm not looking for a perfectly balanced family dog. Similarly, I would probably import Tibetan mastiffs from working lines in their homeland rather than buy from modern western lines if I was interested in that breed in its original form. They have been bred for different traits and a different lifestyle, which is totally fine...but it is why I fully support having varied lines and different types of breeders and purposes. 
Once again here lies the problem, I have no objection either although I do not wan these off colors accept. The breeders who have these dogs do NOT DNA test for PRA, BAER test for full bilateral hearing or OFA for hip and Elbow displasya. That is my huge beef . RESPONSIBLE breeders do these expensive tests as well as promote good temperament! Does anyone really want to buy a dog that is deaf, or could go blind or develop displasya. That is what I am worried about. I guess it is a personal choice, get a dog who can see and hear and live a 12-15 year lifespan or go for the crapshoot. I have seen way too many farm heelers who are blind and deaf for my liking.As for chocolates and creams, I'd like to see actual DNA tests laid out, as that is ultimately worth far more to me than any hypothesizing.
I adore the breed too...and I don't want to see the entire breed limited to one very narrow look.
