Here is a link to the discourse where this "bug" seems to be emerging:-
http://processing.org/discourse/yabb2/YaBB.pl?num=1259153224
Other users have reported the same issue on other platforms (Windows 7, OSX) but my personal
experience is on Ubuntu Linux 10.04. Running either processing-1.1 or processing-0184.
The library that appeared to cause my problem was PeasyCam (version 0.83). Error messages and
further details on the discourse. If I removed the library I could run OPENGL sketches as normal else
got the signature error. This applied to "ALL" opengl sketches including samples!!!

This is caused by library developers who include the OpenGL classes in
their library code, which causes a conflict with the OpenGL library that's
included with Processing.

If you know of libraries that do this, please let us know, and we'll remove
them from the download page until their author fixes the library.

Actually no, this also appears to be a separate OpenGL problem caused by
Sun changing the signatures on the OpenGL download. Grr...