You can bet on that update because any CCFL display is on the chopping block.
I was talking to an investor advisor and while I don't agree they felt that Apple will be pushing some upgrades out RSN to help pop their stock price.
We all know the story and reasons for the move from CCFL (if not, ask).
As I recall, there was some news about Best Buy listing some tracking or stock information regarding different MacBook Pros... Macrumors has this page about it.
More evidence to support an update, within a month or so, comes from good ol' Amazon. Here on their Apple notebook list, you can see that the current models have price cuts, saving about $300 or so on each one. That IS a pretty good deal on the 2.2Ghz model, you have to admit.
Sure, Amazon does rebates and price cuts all the time, but this is a little big, don't you think? So I'm going to guess that Amazon wants to sell off as much of the current models in stock now to make room for the impending Penryn refresh. Of course then you could buy the Santa Rosa ones new-in-the-box for much less, which doesn't sound bad at all. But if you ever planned on buying a 17-inch model from them, I would recommend buying from Apple to throw in all the upgrades, even though Amazon is selling this one for the price of the middle, 15-inch model. Unless you really want a cheaper Mac with a 17-inch screen... I would much prefer the hi-res one though.
Any guesses for when the update will be? I'm thinking it'll be around the SDK release.