When to commit...?

Until the 13" MBPs get the i3 I doubt the Macbooks will.

 

According to the Buyer's Guide it is in mid-product cycle and the buy recommendation is neutral

 

Same boat I was in. I bought my MB 13 two weeks ago. Under normal circumstances, you would expect a refresh in October or November--but these aren't normal circumstances. On one hand, the Core 2 Duo is nearing EOL, and at the same time Intel is poised to release a new chip architecture at the beginning of next year (Sandy Bridge, due Q1 2011).

I went ahead and took the plunge, and my reasoning was this: look around a bit and you'll find the base MB brand new for $850 after rebate. At that price, you can probably resell it in the spring at a very minimal loss and purchase the refreshed model at that time, given that Macs actually seem to retain a good deal of residual value.

Moreover, while the C2D is getting pretty long in the tooth, it's still a perfectly viable processor for virtually any day to day task, and even moderate gaming (which is far more GPU dependent these days). I have a very powerful homebuilt desktop which would shame even the top of the line MBP with its i7M, and this machine feels just as snappy in day-to-day use as that one does. You'd be hard pressed to notice any difference unless you were doing extensive video encoding or something of that sort. I have to imagine that most people looking at 13" notebooks are more concerned with battery life, weight and general portability than they are with finding an all-in-one replacement for a proper desktop machine. That was certainly true of me.

Finally, technology evolves so quickly these days that if you always sit around waiting for the next best thing, you'll be waiting a long time.