Sun has already publicly announced support for the 'Hammer' family. This includes a new version of x86-64 of Solaris and probably some other apps like Star Office, JDK, etc.
AMD's introduction of x86-64 is less risky than intel's IA-64, which is a completly new instruction set. Think of it this way. AMD's expanding the x86 istruction set is similiar to when intel expanded it from x86-16 to x86-32. This was done when the 386 was introduced. The 386 was able to run the old x86-16 code, that was developed for the 286 and previous CPUs, as fast if not faster than the 286, but it could also run x86-32.
By expanding the x86 instruction set to 64bits the 'Hammer' family will be able to natively run legacy software like win9x/DOS, current 32bit software and future 64bit software. On the other hand, intel cannnot say the same for IA-64, which is a brand new instruction set like. Thus, for 'Itanic' to run 32bit software it runs it in a sperate core that is on the same die. 'Itanic's support for 32bit software is inferior to the current Pentium!!!.
PimpinLoon
'Itanic' is a trademark of <A href="http://www.theregister.co.uk" target=_blank>The Register</A> and I used it without permission, but I had to because it is to cool.