(I apologize if this has been discussed---I did a few Google search and didn't find relevant threads, though.)

stockfish is probably the most powerful open source chess engine and I recommend including it in Fedora.  It's easily compiled.  With the executable at /usr/bin, PyChess (which is already in Fedora) automatically finds it as an available engine.

Its website: http://www.stockfishchess.com/

An example spec file: http://www.openmamba.org/showfile.html?file=/pub/openmamba/devel-ercolinux/specs/stockfish.spec

Comparison with other engines: http://code.google.com/p/pychess/wiki/ChessEngines

I set the severity to "low" since I guessed that Chess/Games are not that important to Fedora (I could be wrong), but this one is quite simple to package so I hope it will be included.