After a lot of digging, and a recompile of gcc, I think I've finally got to the bottom of the Java/C++ on Tru64 Unix problem. If you're using threads, you have to compile absolutely everything with _REENTRANT defined. I guess that makes sense, but when there isn't a reentrant version of the standard C++ library, it doesn't make life easy... Wish I could stick to Linux.
Homework: Read up on WebDAV.