Since they are pretty different from each other, it's highly unlikely that you could hybridize them.

I'm pretty certain that it's impossible to cross them, if it was possible, I'm sure that you would have seen them by now. I have "heard" of Coconuts crossed with Queens... never saw one though, but they are both feather leaf palms.

I think its impossible, they are too genetically different. I hear that it might be successful to cross a Butia with a Coconut palm. That would mean that you can have a very coconut looking palm tree in a zone 8 or 9!!
-Alex

Not sabal and coconut. Like tropicalzone7 said above they are to genetically different. The crosses above are real, but what you get from seed is very variable and so is hardiness.
Now I know for a fact they haven't tried
Beccariophoenix and the coconut palm. I think thats the scientific name for " california frozen coconut palm", which is not a coconut palm but a close cousin recently found. No one has a flowering tree yet so everyone is waiting to see. I don't see why they can't try with the mature trees in its natural location but thats all I know.
It looks very much like a coconut palm, check out google images of the two. Its also hardy to I believe 28-29f and can be grown in places with extended cool/mild winters such as SoCal...
If a cross was to be made, it could be interesting, I don't think it would have fruit you can eat but its a could happen. I think these maybe restricted to the higher end of zone 9.
Maybe though though instead of crossing the coconut palm, use this Beccariophoenix instead and it could be alot more hardy.

I think one major advantage to Beccariophoenix to a coconut palm is its great cool tolerance. Its cold tolerance isnt too special (maybe a mild zone 9b location would be its limit as far as cold goes), but they dont mind California's cool and dry weather overall unlike a coconut palm. Coconut palms would be able to survive in Coastal California just based on the lowest night temperatures every winter, but once you factor in the cool days and even cooler nights (even during the summer the nights can be a little on the cool side), its too much for a coconut palm to handle.
Beccariophoenix doesnt look exactly like a coconut and Im not sure how similar it is genetically to a coconut, but its a great substitute for a coconut palm and from a distance, I dont think its easy to distinguish the 2 (especially during early adulthood).
Maybe one day there will be some Coconut palm hybrids. It would be cool to see and would definitely give a tropical look to cooler gardens!
-Alex

I appreciate the answers guys, thanks.

I've been looking at chromosome counts, and they weren't too far off (32 coconut, 36 sabal), but I think the mismatched ones would make for a sterile plant that never fruited. Oh well. us_marine is probably right, with my luck I'd end up with a tree with the cold-hardiness of a coconut palm and the fruit of the sabal. I'll check out that Beccariophoenix though, looks like it will be interesting to read about.

As far as I know, the only successful crosses in palms, aside from those in the same genus, are those in the same subfamily or even subtribe. Any more unrelated than that, they appear hopeless. Coconuts and Trachycarpus are not even in the same family, so that would be a NO. But even in the same subtribe, THEN chromosome counts seem to matter... but there are huge variations at that level (some having counts under 10 while others over 30). So far, only those in the same subtribe and nearly same chromosome counts have worked out... and still, there are dozens of such matches that don't seem to have worked out for whatever problems. There have only been perhaps a dozen or so successful extrageneric palm hybrids so far, and some are really difficult to get to work.

I agree that conventional hybridization methods probably won't work for all the reasons mentioned in this thread. I have no idea if it's being done, but a gene-manipulation method would seem the only option. Something such as inserting a "hardiness gene", if such a thing even exists, and if it's ever isolated. It does seem that some interesting things will be in the future of gardening!

http://en.wikipedia.org/wiki/Colchicine#Botanical_use

This looks interesting... they use it to make wheat/rye hybrids that are fertile. Seems like if you could use it or something like it just on those chromosomes that are mismatched, maybe some hybrids could be possible.

I doubt hardiness is a single gene, it's probably the result of lots of different factors including shorter daylight dormancy and how much water the plant needs and where it is sequestered in the tissues. But yeh, it'd be nice if something could be done. I want a few coconut palms already! ;-)