The esteemed Brad Knowles has said:
Use the latest version of 2.4.x. As you've demonstrated, the 2.5 stuff is not yet fully baked, and Mailman 2.1.8 and earlier are not compatible with it. $DEITY-only-knows what else they're going to break in the process of trying to "fix" 2.5.
I'll update the FAQ Wizard to reflect this.
Thanks for the feedback.
I think that for Mailman purposes, the good news is that the partial build of Python 2.5 using Sun's C compiler has been online "production" for several weeks and hasn't crashed yet. However, after assessing the Python build situation, I think that a back-down to 2.4.4 would be wise.
I did post details of what I've done with the Python 2.4.4 and 2.5 build trees to the python-help mail list. What I got was a suggestion to take it to the python-dev list, which I've done.
At this point, either I'm missing something pretty basic and reinventing the wheel, or I've smoked out some long-standing issues with Python build-install, not all of which are specific to Solaris.
Hank