Hell hammer is right. Rumors are just rumors, but there are some good reasons why it will happen thursday. 1. Steve's birthday is thursday 2. Mbp is due for an update. 3. Everyone is almost run out of stocks. 4. Apple needs to release mbp, so they can be prepared for an iPad in march and April. But again, rumors are just rumors.
Mac computers are oficially second class citizens to iOS mobile devices.... quiet online refresh of MBP's on Thursday and a full event announcement for the iPad a few days later.
See macrumors homepage for brand new rumors on the iPad 2 being possibly released on the 2nd during a media event. IMO the 2nd is not unlikely for the MBP either.