For those users who must see a Stable/Release Candidate (RC) version before installing, the ICS based CM9 has now moved quite a number of devices onto a RC1 stage. The release of the RC builds does not indicate that the nightly builds (Nightlies) have stopped. Nightlies are still progressing and being released as usual as issues get fixed and integrated daily.
The main benefit of being an RC release is that users are now allowed to submit official bug reports whereas previously, users could only post their issues on XDA forums. Also, an RC release indicates that the CM team feels that the baseline is more or less set and they are getting ready to close the remaining issues and march on towards a stable release. As usual, there will be no ETAs and do not ask for one. The developers will release a Stable build when it is ready.