We here at Joystiq like modules quite a bit. As you'll see to your right, our website is adorned with more than a few of them, so we were glad to hear about just how modular the PlayStation Vita's design is, as discovered in a teardown of the device by iFixit. In fact, due to its modular design (among other things), the device was given an 8 out of 10 "repairability score" by the site.
Beyond the thrilling news about the Vita's internal architecture, the site also points out that, despite needing a fancy baby screwdriver, the Vita's internal battery is "definitely serviceable by the average user." It also doesn't hurt that the internals won't cost a ton of coin to replace, if something does break. Should you be interested in all the gory details regarding the Vita's internals -- gory details that our dummy brains can't properly contextualize -- iFixit is more than happy to accommodate you right here.