I recently read at crutchfield that the front center channel on a pro-logic setup is matrixed from the L and R channels. Is this true?

I thought it was a dedicated channel....

Pro-Logic is matrix. Just think about a cable broadcast or a VHS tape: where does it gets the information from? Correct, it matrix decodes it from the stereo track (that's why you can never have DPL from a mono source). It decodes Front L, Center, Front R and Surrounds (L+R). 4 Channels all together.

The huge difference is Dolby Digital (or DTS) where all channels are discrete, so not matrixed.

I think the way it works is that
any information in the R channel goes to the R speaker,
any information in the L channel goes to the L speaker,
any information in both L&R channels and in-phase goes to the center speaker,
and any information in both L&R channels and out-of-phase goes to the surround speakers.

That's why you have to have a stereo source for Pro-Logic -- mono results in a center channel only because the L&R channels are identical and in-phase. It's also why sometimes the surround sound on TV programs cuts in and out -- the signal is phasing (or the broadcaster isn't broadcasting it correctly) and confusing the Pro-Logic decoder.