Back in December of 2011, the T-Mobile Samsung Vibrant was canned by the CyanogenMod team due to a 911 emergency dialing bug that was considered crucial and unfixable:

We are no longer supporting the Vibrant due to the inability to dial 911. We consider the issues related to this unresolvable without source code from Samsung related to the Radio interface layer and its interactions with the Audio layers and have taken the decision to no longer support this. We apologize for the inconvenience and strongly suggest that Vibrant users use a Samsung ROM due to the 911 issues with any ROMs based on open source code. -SGS Team/Team Hacksung/Teamdouche

Vibrant support was officially pulled, tears were shed, and Vibrant owners lost all hope of ever seeing new CyanogenMod builds on their devices.

Good news, everyone (yes, use the right voice)! Turns out the unfixable bug was actually quite fixable after all. A change, authored by Pawit Pornkitprasan (pawitp), reverted the ban earlier today and restored the Vibrant's place in the official CM list:

Revert "Removed Vibrant from list of CyanogenMod devices" Emergency call is fixed and we have a new maintainer now. This reverts commit a42da130069b656c90942640ad9262217d7f04d8.

Awesome. Welcome back, folks. You know you missed us.

Update: I'm pretty sure this is the change that restored E911 support.