Rumor: Older Mac Pros might not get Mountain Lion?

Hi all,

I have a Mac Pro 1,1 system that I bought in Nov. 2007. I'm hearing a rumor that older Mac Pros may not be able to upgrade to OS X 10.8 (Mountain Lion). Has there been any official word from Apple on this?

If this is true, it may be because these Mac Pros use 32bit EFI. I think in late 2008 or 2009, Apple went to a 64bit EFI. I know that this 32bit vs 64bit EFI issue has limited the ability to upgrade my ATI Radeon X1900 video card.

Any info will be appreciated.

Thanks & Enjoy life!
Steven