"Last time I looked the RT DB was ~ 7 to 10 Gig. Oh, I stand corrected, it's not: it's now 28 Gig"
It's apparently about as big, if not bigger, as the main university databases. And sufficiently normalised that it actually has the 10+ million row tables that they don't.
Our RT server is becoming a victim of its own success. The number of new tickets has doubled every year... We'll probably hit 1 million tickets by the end of 2010.