I wanted to second the motion that there may be a problem.
Recently upgraded to xdoclet-1.2 (official release) and it seems to have coincided with that.
Running j2sdk1.4.2(03), ant 1.5.x or ant 1.6. We have large, iterative build scripts. Eventually, we run OutOfMemory. When you re-try the task (with less out of date targets), everything succeeds.
I have ANT_OPTS including -Xmx900m but the process doesn't seem to be getting up over 250m.
Anyone have any suggestions?