Some of the Xilinx tools (notably EDK and the 9.2 PRFlow) use xilperl which requires libdb-4.1, the oldest version available in the repository is libdb-4.2. The solution is to go to /usr/lib and make a softlink from libdb-4.2.so to libdb-4.1.so. You should now be able to use xilperl without any issues.
Some versions of Planahead when used with Ubuntu have an issue with the Java Runtime that causes a blank Planahead window to appear. The solution is to set the following environment variable: export AWT_TOOLKIT=MToolkit