If you are looking for a free software for debugging and profiling x86 Linux programs, then Valgrind is the right tool. It helps you in detecting memory management and threading bugs. The Valgrind distribution currently includes five tools: two memory error detectors, a thread error detector, a cache profiler and a heap profiler.

A very nice tutorial “Developing with Gnome” is available at newren’s site. There is a chapter which gives detailed instructions on how to build Gnome from CVS.