With rvm installed globally for all users, the rake plugin has difficulties to find rake when using gemsets.
RVM is installed as a global installation under /usr/local/rvm with the global /etc/bash.bashrc script modified as advised in the rvm documentation.
Hudson is running under the tomcat6 user, which has no own bashrc script, since it's a no-login account.
The "rvm installation path" is set to /usr/local/rvm in the plugin configuration via the Web Interface (Hudson Configuration => System Configuration), and rvm installation (including gemsets) are recognized, since I can choose them in the rake version dropdown in the project configuration.
However, when I choose a rake version with a gemset, (say ruby-1.8.7-p302@my_rails3_gemset), Hudson reports "FATAL: /usr/local/rvm/bin/rake doesn't exist".
Issuing the following commands from the Linux shell produces the following output: