If there is it will only likely to be an option to BTO for a 2.8GHz i7 CPU. Yes it may save you some time compared to the 2.66, but that'd be negated by the wait for it to be released.
Just go for the current i7, it's a fast machine and runs great. If you wait for the speed bump then "there'll only be a few months to Sandy Bridge", so you wait again? Don't get caught in the waiting trap, I did that with Arrandale and it wasn't pleasant.
This is sound advice.
I needed a laptop at the end of September / beginning of November 2009. I remember because I JUST missed the back to school iPod special. There was rumor that the Arrendale processor refresh was going to happen at the end of November. So I waited. The regular Macbook was refreshed but not the Pro line.
A series of more rumors that an upgrade was going to happen in December, January, February, etc. all occurred and did not come to pass. Finally, in mid to late April 2010 the refresh to the Pro line happened.
This was after my first two semesters of school. Now I got by between my giant and heavy gaming laptop and my tiny netbook. But it was a pain switching between the two, doing real work on teh netbook sucks, and the gaming laptop took too much room on the school's desktop area. I REALLY could have used a nice 15" laptop. (and sold the others)
However, I got stuck in the waiting game because the refresh "was going to happen next Tuesday" over and over again.
Don't be stupid like me. If you need it now, get it now. The only things the next refresh are likely to have are: 1) a slight boost in processor (not a major jump like core2duo to arrendale, but just a modest ghz buff; 2) there is a possibility of lightpeak i suppose but unlikely; and 3) perhaps better heat dissipation.
None of those are things are worth holding your breath for. Lightpeak is the most interesting thing, but it will not likely happen until the sandy bridge update, and even when it does, it will be so new, you'll have trouble finding things to connect with it (at first anyway). A slight bump in processor speed isn't going to make a huge difference. The heat situation isn't that bad, but they do get a bit toasty in the left hinge area.
If you bite now and find out later that you absolutely must have whatever comes on the machine that got a refresh down the road, you can always sell what you got now and buy the new one. Macs seem to hold their resale value unlike other brands.