Buying anything now is just not a good idea IMO, i mean 10 days away and you'll be paying the same price as you would a core duo for a core 2 duo so why not just go with the one with the most bang for buck. Plus there is a widespread of issues surrounding the MacBooks (random shutdown)
If you're planning on getting a MBP, which is most probably getting revised at WWDC and if you don't care about the Core 2 Duos then you might also see a price drop in the currently offered MBPs with the Core Duo, if they are still being offered of course. Here's another reason to wait.
I am wondering about the same thing. Should I wait the 10 days? I know it is highly unlikely that they will update the macbook line but there is always a what if.