As you are probably aware, Linus Torvalds had decided to bump the version number of the upcoming Linux kernel to 3.0. The development for Linux 3.0 has been going on for a while with the first release candidate being released on May 30th.
The sixth release candidate was supposed to be the last one. However, Torvalds has decided to have one more release candidate Linux 3.0 rc7 mainly because some testers have found the RCU (Read-Copy-Update) to hang at boot time.
This is what Torvalds wrote to the mailing list announcing the seventh release candidate of Linux 3.0:
I think I said -rc6 might be the last -rc. I lied.
Things have been pretty quiet, but there’s enough new stuff here that I wanted to do another -rc, and we still have some issues with the RCU changes causing problems when RCU events happen before the scheduler has been fully initialized etc. So -rc7 is out there, although it might not have mirrored out to the public sites quite yet.
As with all the previous releases of the Linux kernel, Linux 3.0 will not have any new big features. It will have only incremental improvements. If you are interested, you can check out the changelog for Linux 3.0 rc7 here. At least one more release candidate is expected before Torvalds announces the stable Linux 3.0.
Linux 3.0 has already been adopted by the development versions of many Linux distributions. Debian Wheezy has already been moved from Linux 2.6 to Linux 3.0. The latest development release of Ubuntu 11.10 too was based on Linux 3.0.