For the B&N Nook to be rooted - that is, broken open and readied for software modification - is one thing, but the real reason people are excited about hacking this ereader is obvious: they want apps. And apps they will have.
Users at Nookdev are reporting that, after a little clever input tricker, they've managed to get the Pandora radio app running on the Nook. At this point the install process is still pretty intimidating: the rooting procedure itself requires a screwdriver, a microSD reader, a computer running Linux and comfort with the command line, while app installs require setting up a VNC server on the Nook (touchscreen controls evidently don't work properly yet) and launching from an ADB shell session, since the app launcher doesn't work yet. If this sounds overcomplicated, that's because it is.
But the point is, hey, Android apps on the Nook! Pandora's just the first, but a web browser, email client and a new homescreen can't be far off. That's when things could get sticky for Barnes & Noble, whose telco partner, AT&T, probably won't be too happy about a slew of Nook users trying to use their device's free data connection for doing more than downloading ebooks. They had to know this would happen, so I'd expect there to be a few roadblocks between hacked apps and the Nook's 3G connection, but who knows? Virtually nothing about the Nook's launch went exactly to plan, so who's to say this will?
Either way, Nook: hacked. Interest: piqued. Eyes: peeled. [Nookdevs]