This actually is yet another installing Linux on some other vendor’s device story. Android is, after all, built around a Linux kernel although the rest of the software stack is quite a bit different.
In this instance, Wired covers a do-it-yourselfer who replaced Windows Mobile 6 with Android. He also published a fairly accessible guide for anyone else intrepid enough to try the switch. The phone in question is made by a manufacturer, HTC, that makes a lot of phones that come bundled with Android. It doesn’t seem too surprising then that this sort of firmware re-flashing would work out pretty well. There are a couple of glitches reported by some users, but nothing major or even as complaint worthy as the sluggishness of the original OS.
The article explains a lot more about the appeal and process of re-flashing. The main driver is similar to why even owners of the latest generation phone jailbreak or root their devices. Installing a custom firmware has the potential to make the phones run better with more features at the possible risk of turning it into a useless brick in the process.