The i3 isn't a big deal (not when compared to the e8600 3.33 model). The i5 upgrade that's now available for the 21.5 at 3.xghz is huge though. That model will probably bring on a lot of purchases from those who were waiting for something powerful in the smaller model.
Oddly, it's faster (as far as I can tell, without the processor details) than the one in the 27" model.