Well, through a series of events I won't bore anyone with, I wound up selling my 13" i5 2.3 GHz and buying a 13" 2.4 GHz i5. The only difference that I can discern is that the newer 2.4 has a slightly faster processor and comes with a 500 GB hard drive, vs. the 320 GB drive of the 2.3. In terms of appearance, feel, etc., they are identical. Perhaps "duh" is in order, but worth noting. In performance terms, the newer machine is, as you would expect, ever so slightly faster. Can you tell in normal use? Absolutely not. Only on Geekbench and CineBench can you tell the difference. My 2.3 i5 scored 6030 on Geekbench (32 bit), the 2.4 i5 scored 6230. Cinebench showed a slightly bigger difference, but still nothing to get too excited about. No clue why, but the 2.4 i5 did edge out the 2.3 i5 on the OpenGL test, 6310 to 6125. I'd have expected them to be identical given the identical graphics unit. The same was true in my normal use. I'm darned if I could sense any difference in even large iPhoto, iMovie, or iTunes tasks. The new one MIGHT have felt a TRACE quicker on iMovie rendering, but that could also just be me expecting/wanting it to be a touch faster. Office, web stuff, etc., was identical, at least to my perception. The only thing I consistently noticed was that the new one seems to be integrated with Lion a bit better - it just seems to beachball a bit less, and it seems like some Lion specific features ran a bit faster and a bit more reliably. Not a huge difference by any stretch, but it was the one thing that I consistently noted. Overall, if you have a 2.3 i5, save your money for the Ivy Bridge refresh - I'm comfortable saying the new 2.4 is nothing more than a spec bump done more for marketing purposes than any performance problem. Of course, the answer is probably different for the 15" base MBP, which got what looks to me to be a fairly significant upgrade. In terms of value, the base 13" does look to be improved - mainly due to the larger hard drive. It remains, in my opinion, a significantly better value than then any of the Airs, and remains a great introduction to Apple's laptop line.