A few days after releasing the Android 2.3 SDK, Google officially pushed Gingerbread to the Android Open Source Project (AOSP). Shortly thereafter, developers (such as the CyanogenMod crew) immediately started working on their custom ROMs based on the AOSP code (e.g. CyanogenMod 7).
It has only been a few days since CyanogenMod released version 6.1.1, their most recent stable update, so it's still likely to be a few weeks before a stable release of CM 7 is available. Nevertheless, a group of eager CM developers and enthusiasts have taken the liberty of packaging early unstable releases of CM 7 (with Android 2.3 Gingerbread) for a variety of Android devices.