Found here: http://www-106.ibm.com/developerworks/library/l-ivit.html?n-l-9262 the following:
W: But the trade-off is that you break backward compatibility to get there.
Mosberger: From a technical point of view, it's clearly what you want to do, and it's not quite correct to say it's breaking backward compatibility. Itanium is as backward compatible as anything else out there. The performance of x86 code isn't all that great, but quite frankly I use it every day to do Acrobat, Open Office, RealPlayer, those kinds of things. I think that point is overstated, especially for Linux, because all of the important open source software has been ported to 64-bit and recompiled native for IA-64, so the only things you need to run in emulation mode are those proprietary apps that, for whatever reasons, you can't get natively. And for those, it's just fine. Last week, I ran TaxCut under WINE on an IA-64 Linux machine and it worked fine -- even performance-wise.