Maintenance for the week of October 7:
• PC/Mac: No maintenance – October 7
• Xbox: EU megaserver for maintenance – October 9, 2:00 UTC (October 8, 10:00PM EDT) - 16:00 UTC (12:00PM EDT)
To be precise, the current Mac minimum requirements have been in effect since 4/29/2015. The most current version with a date stamp can also be found here. OpenGL 4.1 is not yet in active use by the most recent ESO client version, but will be in a future upcoming update (no ETA announced as of yet).
Please refer to this extensive Apple FAQ on which Mac models and OS X versions are capable of being upgraded to the current OS X 10.10 Mavericks. There's also a chart showing which GPU models support OpenGL 4.1 in OS X 10.9 and up.