RT needs an O'Reilly book. We'll know RT has arrived when it has its own book. Looking at how much it seems to be in use, I'm guessing that may be soon. (Gnat?)
I might sound like an anti-business guy or something, but I look forward to seeing large-scale proprietary systems supplanted by open source alternatives with freedom. I hope BestPractical (the company that supports RT) is making out good on their business model. Going further I sometimes imagine OS and RDBMS vendors gradually adopting this business model.