Python seems like a weird choice for writing a SIP switch. It seems like you would want to write that sort of thing in C, for much the same reason apache is written in C.
Then again, I've never worked with SIP, so maybe I'm off base here.
I do think there's a desire for a language that's lower level than Python/Ruby/Perl, but higher level than C. Java and C++ sort of fill that role, but poorly. I'm hoping that I'll get a chance to test out Google Go to see if it works for that.