I'm with you. For the iPad2 I expect a February announcement with shipping in March. I think towards the end of this month could have been the iPad2 announcement alongside the new publication app mechanism.
But Steve's leave of absence... I'm sure things are going to be delayed somewhat.
I have been expecting a March announcement and late March/early April delivery for the new iPad. I guess they could do a late February announcement.
One thing to consider is that the Chinese New Year starts on Feb 3 which means nothing gets manufactured or shipped for two weeks. Even if the production lines are ready to produce at anything resembling mass production runs, there will be a delay to build inventory for the launch. I am guessing that they would need a minimum of 500,000 units at launch which, at a build rate of 25k/day, would take 20 days. In truth, I think they will require a larger number at launch - probably 800-900k.
I don't think that Steve's absence is likely to affect the launch. If he is well enough, he will do the presentation; if not, Apple will take the opportunity to showcase their other executive leadership.