As someone who recently checked in patches to get perl 5. to compile on SCO OpenUNIX 8, my opinion is pretty clear on that subject. (And I have to say that OpenUNIX 8 is the most unstable OS I've ever used.) But that's apparently not the common advice everywhere.
If you get gcc 3.3.1, you'll see a README.SCO file in the tarball.
May I quote part of it
We have been urged to drop support for SCO Unix from this release of GCC, as a protest against this irresponsible aggression [the lawsuit] against free software and GNU/Linux. However, the direct effect of this action would fall on users of GCC rather than on SCO. For the moment, we have decided not to take that action.
What would happen if gcc begins to be incompatible with SCO ? SCO will ship more copies of their crappy compiler. People who absolutely need gcc will maintain their own fork. No decent debugger will be available for SCO anymore. Users will be hurt, evil companies will be pleased.
Update : hey, slashdot has the story too.