While GCC 4.10 is the current release under development since the GCC 4.9 debut this spring, GCC 4.10 will likely be relabeled as GCC 5.0. There's a fresh thread on the GCC mailing list that talks about GCC version bikeshedding.
Jakub Jelinek of Red Hat originally brought up the generally agreed idea of releasing GCC 5.0.0 around April 2015, GCC 5.0.1 around June~July 2015, and GCC 5.1.0 in April of 2016. But the minor/patch version number handling is still being discussed such as whether there would be a GCC 5.0.1.
Some developers have already voiced objections to bumping the major version number every year, with the plan of seeing GCC 5.0 in 2015, GCC 6.0 in 2016, GCC 7.0 in 2017, etc. We'll see how the GCC version proposal shakes out so stay tuned for more details on Phoronix but for at least right now it looks like GCC 4.10 is going to become GCC 5.0. It's worth mentioning that in the past ideas have been expressed about GCC 5.0 from signifying its modularization like LLVM to other improvements.