"They get the credit for Intel's work."
Doubt it. Not really sure when IBM introduced the Power3, but I found a SPEC score from 1998, so it was at lest by then.IBM introduced a 64 bit version of their mainframe in 2000, but it doesn't look as if they had an 64 bit OS for it until 2001. Of course, just because it wasn't released doesn't mean it didn't exist for IBM's people to do the DB2 port to it.
Making DB2 64 bit clean almost certainly happened well before they started work on the Itanium port. Given that about the only simularity between the Opteron and the Itanium is use of 64 bit registers and the ability to address more than 32 bits of memory for a given process, it is highly unlikely that any of Intel's work was leveraged into the Opteron. However, making DB2 64 bit clean for their own products did likely ease the port to Itanium.
Wanna, I know you aren't as dumb as you are pretending here. Get a little dose of reality, why doncha?