From the man himself:
So there it is. Gone are the 2.6.
days, and 3.0 is out.
This obviously also opens the merge window for the next kernel, which will be 3.1. The stable team will take the third digit, so 3.0.1 will be the first stable release based on 3.0.
As already mentioned several times, there are no special landmark features or incompatibilities related to the version number change,
it’s simply a way to drop an inconvenient numbering system in honor of twenty years of Linux. In fact, the 3.0 merge window was calmer than
most, and apart from some excitement from RCU I’d have called it really smooth. Which is not to say that there may not be bugs, but if
anything, there are hopefully fewer than usual, rather than the normal “.0″ problems.
Download from your chosen distribution’s repository or directly from kernel.org.