I had a chance to do a quick side-by-side comparison of my wife's mid-2007 SR 15.4" MBP with my new 15.4" Penryn 2.5 GHz MBP. Some brief observations: > From what I can tell, port locations, DVD drive and overall case are exactly the same fit, finish, locations, etc. > The backlit keyboard on the Penryn MBP has a slightly more bluish tint, but I don't think it's as blue as the picture on Apple's web site. It's a good shade. > The Penryn MBP runs MUCH cooler. Running the same tasks, it never became uncomfortably warm like my wife's MBP. > Web pages seemed to open about the same speed, but my web pages tended to hang a couple of times while loading. > The key markings on the keyboard are set up more like the standard Apple iMac or external USB keyboard (see other threads on this). > Office-type applications do not open noticeably faster on the Penryn, but these applications aren't very resource intensive. > No yellow tinting issue in either MBP,other than the usual yellow tinting when viewed from off-center. > I love multi-touch. Zooming on photos and text is great. > Mine looks newer! I'll add more if I find any real differences, or let me know if you want me to look at anything specific.