The most recently posted snapshot (20041007) combined with the recently submitted patch (20041007-solaris) results in a vim4j tree that succesfully builds and runs on Solaris! This version should also build and run on both Linux and Macintosh OS X (Darwin). You will likely still want to apply the above patch, since there is at least one non-Solaris fix in there. I am still working on the Windows build.
After downloading the snapshot and applying the patch, from the root of the source tree:
BUILD IT WITH: cd src && ./configure && make
RUN IT WITH: ./vim -g
The next upcoming release, 0.0.7, should include all of these fixes and should build on all current targets: Linux, OS X (Darwin), Solaris, and Windows.