It seems very likely that the recent 2.6.39 Linux kernel was the last major release of the 2.6.x series.

Linus Torvalds made a remark on the Linux Kernel Mailing list at the beginning of the week that the voices were telling him that the numbers were getting too big… and they are..aren’t they?

More than the numbers inside of 2.6, the time has come for change, for a number of reasons. Torvalds gives at least one good reason related to timing:

“So I’m toying with 3.0 (and in that case, it really would be “3.0”,
not “3.0.0” – the stable team would get the third digit rather than
the fourth one,” Torvalds wrote. “There’s also the timing issue – since we no longer do version numbers based on features, but based on time, just saying “we’re about to
start the third decade” works as well as any other excuse.”

I have to admit that my initial reaction was NO, a version change indicates a binary compatibility change, but that’s not really the case here is it, since it’s time based.