Dissecting the HTC Evo revealed no great secrets other than that it's very easy to disassemble, which will make it easy to replace broken glass screens. In terms of random factoids? There's a wetness indicator on the battery. [ifixit]

Edit: Apparently the moisture indicator on a battery isn't so new. So you get a bonus factoid. Are you ready for this? Are you sitting down? RED INNARDS! LIKE IT'S BLEEDING!