Part of me thinks this could be very good. I've always been a bit leary of going to AMD CPUs because it seems like their chipsets are a bit questionable. (yes, things have improved dramatically in the last few years with NVidia's chipsets, but incompatibilities still loom-- ask the X-Fi owners!) Companies can, and do, test on Intel chipsets. But there are a lot of AMD chipsets just floating out there, kinda buggy, mostly working but sometimes not..
[I know, I know, lots of people have perfectly working AMD machines, but it does seem like there are always weird esoteric issues that end up being traced back to obscure bugs that no one discovered in the chipsets]
I would assume ATI will now have everything they would need (and AMD would demand) to produce pretty solid chipsets for their CPUs...
Of course, this all happens now that Intel is (for now) taking the lead in CPU power..
I think it SHOULD be a good thing, might be a bad thing, but I assume it'll create a very interesting company that SHOULD be able to produce a pretty solid lineup of products.