Java 1.3.1 fcs "javac" in it's default gentoo form would not build ant 1.5 (which , probably because of this, is not keyworded for ppc). It fails with java "Out of memory" errors. However, keywording the ebuild for ppc, and running `THREADS_FLAG="green" emerge ant` from bash will ensure only green threads are used and not linux native ones, which lets the build complete. This environment variable can just as easily be added to the ebuild. Ant 1.5 works well now, as far as I can tell.
No, there are numerous problems with ant 1.5; it will not make it in the upcoming Gentoo 1.4 release.
I've talked to our PPC experts, which report that there are no newer versions of the JDK available for the PPC. Unless you have any better suggestions, I'll modify the /usr/bin/ant script so that it switches ant to green threads permanently on the PPC.
Fixed in dev-java/ant-1.5.1-r1. I've tested it on a ppc. If it doesn't work, please reopen and give me some hints.