Hi.
I'd never heard of Ceglia until a few days ago. Mark certainly didn't tell me about him, just like he didn't tell me about the Winklevosses. By the time Mark talked to me in person he was already a member of houseSYSTEM's facebook.
Here's the timeline of events from my company's trademark proceedings which were filed based in part on the claim (at the time, which has now been settled) that "facebook" is a generic term, as others have discussed here.
http://www.thinkpress.com/authoritas/timeline.pdf
If Mark was toying with this idea in April, 2003 (as I was), then he only started really taking it seriously once he saw my progress, which I'd started on independently. Three days after we had dinner he registered thefacebook.com without telling me.
I don't think Ceglia is arguing that he came up with the idea--he was just funding Mark's idea. So essentially Mark and I thought up a solution for the lack of a universal face book at Harvard at the same time, but I actually made mine before he did, and then I asked him for help running it. He turned down my request and instead asked me for help with an unspecified idea, which I declined to help with since he wouldn't tell me anything and had just been disciplined for ignoring privacy issues I considered important.