MBP and MB will not be refreshed until Sandy Bridge comes out early 2011.
This may or may not be true.
There are speed bumps for the current gen processors coming in the fall (I don't remember exactly why or how or what), but there's a mid-generation bump coming. Apple may or may not choose to embrace it. What I'm hoping is they do, and throw in something like making high-rez standard (if it's only a $90 upgrade, that's not inconceivable). Add in a small boost in HD capacity and a little something else, and you have a cheap upgrade for the holiday season, and to tide people over until your complicated Sandy Bridge models are ready. With the differences in microarchitecture, and the big change to the GPU, it seems reasonable to assume it'll be complicated for Apple to sort out it's GPU switching/OpenCL/Grand Central/etc etc. So I think a April '10 - November '10 - April '11 (or even June '11) schedule makes more sense than a April '10 - Jan/Feb '11. There as a 10 month gap between last updates (June '09 - April '10) but that was the exception, not the rule (we all hope).
Regardless, the one thing you can count on at this point, as people waiting 6 extra months for Arrandale, day by day, should have learned is that there WILL be Best Buy SKU leaks, and there WILL be extended shipping times in Europe and at major US partners, and that until those sorts of things happen, waiting Tuesday after Tuesday for an update is a waste of time.