Not at the moment, but our interrupt overhead and number of background tasks is so low it's something we're thinking about. Is there a specific scenario you're trying to enable?
Meanwhile, it's nice having the support of lots of Linux software so it's hard to justify switching to a non-real-time OS with much less support.
I've noticed, browsing the RPi forums, that people are disappointed that they can't get real-time behavior from Raspbian.
It'd be interesting to see more information about licensing for Minoca, as I could see it as an interesting alternative for small projects on the RaspberryPI.