Talk about a blast from the past: the Sprint Galaxy S II, released way back in 2011, now has official CyanogenMod support. Most of the other international and regional versions of the GSII are already supported to some degree, but I'm sure there are more than a few Sprint customers who are happy to see the most popular custom ROM family come to their devices. There's one nightly of CM10.1 (Android 4.2) available at the time of writing.
The phone's official title is the Sprint Samsung Galaxy S II Epic 4G Touch, because someone at Sprint knows how to start naming a device, but doesn't know how to stop. (To their credit, they eventually just started calling it the Galaxy S II.) CyanogenMod goes by the model number, D710. It's a bit of a bummer that the nightly channel for the newly-supported phone hasn't been updated to CyanogenMod 10.2 (Jelly Bean 4.3). The CM team is working hard to get its official devices up to date, but considering the older hardware (the 1.2Ghz Exynos 4210 CPU in particular) it may take a while, if it's even being planned at all. The AT&T GSII is still on CyanogenMod 7, the T-Mobile version is on CM10.1, and the international version is on CM10.2.
As always, you'll need the updated Gapps package if you want access to the Google Play Store, and it's a good idea to make a backup of a stable ROM before flashing a nightly build. Those ROM addicts who are on the cautious side, if there are any, may want to wait for a release candidate or stable version.
Source: Get.CM D710 Download Page