Hm. Well, unbeknownst to me, apparently Apple have updated my ant to 1.8.1. Here's the beginning of my diagnostics output, maybe differences from that will be a clue:
> [ptw@padme trunk-3 12:28:59]$ ant -diagnostics > ------- Ant diagnostics report ------- > Apache Ant version 1.8.1 compiled on September 21 2010 > > ------------------------------------------- > Implementation Version > ------------------------------------------- > core tasks : 1.8.1 in file:/usr/share/ant/lib/ant.jar > optional tasks : 1.8.1 in file:/usr/share/ant/lib/ant-nodeps.jar > > ------------------------------------------- > ANT PROPERTIES > ------------------------------------------- > ant.version: Apache Ant version 1.8.1 compiled on September 21 2010 > ant.java.version: 1.6 > ant.core.lib: /usr/share/ant/lib/ant.jar > ant.home: /usr/share/ant/ > > ------------------------------------------- > ANT_HOME/lib jar listing > ------------------------------------------- > ant.home: /usr/share/ant/ > ant-antlr.jar (5758 bytes) > ant-jai.jar (22282 bytes) > ant-jmf.jar (6747 bytes) > ant-junit.jar (97583 bytes) > ant-launcher.jar (12312 bytes) > ant-nodeps.jar (409067 bytes) > ant-swing.jar (7565 bytes) > ant-testutil.jar (15199 bytes) > ant.jar (1516775 bytes) > > ------------------------------------------- > USER_HOME/.ant/lib jar listing > ------------------------------------------- > user.home: /Users/ptw > ant-contrib.jar (194050 bytes) > catalina-ant.jar (20418 bytes) > jing.jar (708436 bytes) > js.jar (871260 bytes) > serializer.jar (188993 bytes) > xalan.jar (3078593 bytes) [...]
