If you haven't been following the updates on its progress, here's a quick recap: It's based on Android 2.3.3 Gingerbread, it's got built-in root access with all the command-line goodies, Apps2SD capability (built-in), Incognito Mode for the Android Browser, built-in CPU frequency adjustment and scaling (including overclock and choice of governor), loads of UI improvements and interface tweaks, OpenVPN and SIP calling settings, USB/WiFi/Bluetooth tethering, FLAC support, an FM Radio player, and loads of other features and enhancements.
It's even got a one-click UI theme-switcher that T-Mobile helped develop (open-source, no less).
Even if you aren't into flashing custom ROMs on your expensive new smartphone, you have to admit that this release is a pretty great thing... After all, it means a fully-functional version of Android 2.3.3 is now running, with loads of bells and whistles, on about 30 devices whose manufacturers and carriers are simply too lazy to update.
Alright, enough jabbering. You can learn more about the ROM at CyanogenMod.com, or jump straight to the download mirror if you already know what you're doing!