January will bring a redesigned 17" MBP. We might also see the "mysterious" new product, if it even exists.
Q3 and Q4 will bring MBP speedbump and Nehalem processors. Snow Leopard will be released somtime in the summerperiod, along with iLife 09.
These are my predictions, allthough I have no more knowledge than anyone else on these boards. I'm pretty sure though, that there will be no 15" MBP bump in early 2009.