I think I can fill the role of minor critic ;-). A couple points/questions:
What role do you see C having in this? The most critical aspects here seems to be the webserver and database - both of which are already in C. If you're using perl at all, which you say you are, I'm not sure where else you plan on drawing the lines.
What platform(s) do you plan to support? If it includes Windows, is there a plan for this? I presume IIS support is right out.
Your choice of DB is interesting. Without attempting to start a flamewar on this, I'd like to point out that flamewars on choice of DB happen. Depending on how large you see this growing, you may be alienating many potential users. Are you planning to have a database-abstraction layer to allow Oracle, DB2, and PostgreSQL bigots all have their chance to implement drivers for their favourite database? How will that look?
Javascript seems to be a sore point around here sometimes... ;-)
Ok, that's about all the critiquing I can do... ;->