It's not too much of a surprise OpenGL 3.3 / GLSL 3.30 support is already here given that most of the remaining work was just writing test-cases and verifying the implemented GL extensions and GL Shading Language changes were functioning as expected.
Kenneth Graunke of Intel sent in the last three patches for GL 3.3 and also bumped the Mesa version to 11.0. However, it hasn't been agreed upon yet whether it makes sense to bump the version number to 11.0 given that 10.0 hasn't been released yet.
This next Mesa release, regardless of whether it will be called 10.0 or 11.0, is due for debut by the end of November.
While there's now complete OpenGL 3 support in core Mesa and the Intel DRI driver for Ivy Bridge hardware and newer (Sandy Bridge is limited to OpenGL 3.1 right now due to incomplete geometry shaders support), the Radeon and Nouveau Gallium3D drivers still have some work ahead before they are GL 3.3 / GLSL 3.30 compliant. There's also a lot of work needed for OpenGL 4.x support in Mesa.