NeoOffice, the Mac OS X native port of OpenOffice, is running a fundraising program to support the Mac Intel port. "Members" get early access to the Intel test version. You can pay a small amount of money for early access to just the Intel port (NeoOffice 2.0 Alpha Intel), or you can buy a full subscription to early access to every 2.x release. If the speed difference between NeoOffice MacIntel and NeoOffice PPC is as good as Eclipse on MacIntel vs. Eclipse on PPC, this'd totally be worth it. And of course, the final product will still be freely distributed and open source.

OpenOffice itself does have a Mac version, and it does run fine on MacIntel computers. OpenOffice requires that the X windowing server be installed, which you can find on your Mac OS X install disc (as an optional component that is not installed by default). The latest versions of OpenOffice for Mac OS X can automatically open the X server when you try to run the program. There are user interface differences that make NeoOffice a better choice than OpenOffice for regular use on a Mac, but OO does run just fine.