I think there will be a spec bump late 2011 and a complete redesign in 2012.
Wait? depends on how much you need it.
Why would the do that O-o.
Because they can, it will make their product more competitive and because it said so on one of the rumor websites (forgot which one).
Still not sure of course but according to the Macrumors buying guide it makes sense.
Recommendation Buy only if you need it - Approaching the end of a cycle
Last Release February 24, 2011
Days Since Update 151 (Avg = 215)
https://buyersguide.macrumors.com//#MacBook_Pro
MacRumors said:This page provides a product summary for each Apple model. The intent is to provide our best recommendations regarding current product cycles, and to provide a summary of currently available rumors for each model.
This page is based on rumors and speculation and we provide no guarantee to its accuracy