Since the previous OpenGL status last April, the OpenGL drivers ecosystem has significantly changed.
Going from OpenGL 3.2 to OpenGL 4.1 for Apple is great. However, considering that Apple took 3 years for that... At least, it's great for OpenGL programmers because it means that we will be able to target OpenGL 4 hardware.
It seems that AMD has released an OpenGL 4.3 driver but as I don't have an AMD card at the moment so I haven't tested it. Also, according to Brano Kemen, Catalyst 13.8 causes a performance drop and glClientWaitSync is particularly slow (> 7ms in his case).
Intel continues to work hard on its OpenGL implementation reaching OpenGL 4.2. According to my sample tests, the implementation works pretty well and it also provides the big OpenGL 4.3 extensions: GL_ARB_compute_shader, GL_ARB_shader_storage_buffer_object, GL_ARB_multi_draw_indirect and GL_ARB_program_interface_query, Considering how far Intel was just a couple of years ago, it's fantastic. I wouldn't be surprised if Intel manages to release at Siggraph 2014 an OpenGL implementation on part with latest specifications at the time.
Mesa is a bit of a disappointment considering that geometry shader is still not supported so we are bound to OpenGL 3.1 on this platform.
OpenGL 4.4 being a small update, NVIDIA had no trouble to ship a good OpenGL 4.4 implementation at Siggraph.
Once again, don't forget to contribute to the OpenGL community by reporting your bugs!