Sam460EX is a way to give new HW (instead of clunky old one) to the AmigaOS, Altivec isn't used in Amiga software at the moment (with the sole exeption of mplayer) so it's basically irrelevant.
Actually, Altivec isn't irrelevant. It is used (albeit not as extensively as I'd like) in MiniGL, the avcodec library, and IIRC, some other parts of the OS too. Even if it weren't used at present, it's important enough that Freescale have finally decided to add it to their QorIQ range of processors. About time! It would be nice if Applied Micro could follow suit; their new dual-core PowerPC processor would be a lot more interesting if it included altivec.
The Sam 460ex is meant to be a low-end machine. It may not have altivec, but it's still a nice machine. It's a good step up from the Sam 440 series, and I prefer it over my A1-XE G4. Why? Mainly because of the PCI-Express bus and faster RAM.
Having said that, I'm still getting an A1-X1000.
Hans