Hmmmmmmmm....
I reckon we could see a spring/summer refresh.
The MBP is mid cycle according to Macrumors at the moment with 76 days before the average update time is up. If we now move to our calenders we can see that 76 days from now takes us to some time in May. The WWDC is in early June, so the average time comes up just before this happens.
Such rudimentary mathematics brings me to believe that we shall have a WWDC refresh of the MBP or possibly before. I think WWDC is likely because the MBP is aimed at the professional market. This would result in the product being released after its average is done, which I would put my money on.
That's the other reason I'd probably disagree with xlii's prediction, the MBP is a pro laptop for 'Serious Business®' and the Macbook is aimed at the education market, far more than the Pro is.
The other possibility, is that the new MBP is released before the WWDC by possibly several months. It could be timed with a new iMac to hit the Leopard release date, some time in spring, which suggests April or May to me, May isn't far off the June WWDC so I doub't they would hold a separate event so close to the WWDC, but April looks like a possibility.
Another thing they could tie it in with is the release date for Adobe CS3, has that been announced yet? I don't know, if you do post it and we can see. As CS3 is such a key product for Apple, it would make sense for them and Adobe to have a big bash at the Moscone centre with Steveo getting the chance to shake hands with the big graphic cheeses at Adobe, a joint release would offer a big boost to both products
I'm not getting my hands on anything till June either way, when my GCSEs finish and its my birthday, so these are just the musings of a procrastinating teenager.
I have no relation to anything that's 'in the wheels' at Cupertino, but that's what a lowly student came up with based on pre-announced Apple dates and average refresh times.
Now I must go and simultaneous equation. *Sigh*