Even the HTC HD2 being a couple of years old, you can install Android 4.1 Jelly Bean on HTC HD2. The HTC HD2 or HTC Leo in different name is supposed to be runs Windows Mobile 6.5 but in some creativity hands, HTC HD2 ported with various Operating System such as Windows Mobile, Windows Phone, Ubuntu, and various Android OS version. Or perhaps next Firefox OS could be port also on HTC HD2.
And now the HTC HD2 runs with the latest Android OS version, Android 4.1 Jelly Bean. But this is not stable version and not recommended for daily use. For now it just a proof of concept that HTC HD2 could run Android Jelly Bean and needs many developers to get very stable version. This is the port of Android Jelly Bean pre-alpha version.
However some features have been working such as mobile data 2G/3G, calls, WiFi, Bluetooth, SMS, sound, video playback, and USB mass storage. But some home works need to be done because some of features are not working properly such as browser, error happen when installing some apps, and Google Now crashes.
The HTC HD2 with Android 4.1 Jelly Bean runs with kernel from Tytung for now but might be some users use others kernel, you also must notice the amount of disk partition which using on HTC HD2 to get Android 4.1 Jelly Bean running. If you interesting to bring your HTC HD2 a new live, just follow some instructions from original page. You can find also the download link to download the ROM to install Android 4.1 Jelly Bean on HTC HD2.