Maintenance for the week of September 22:
• NA megaservers for maintenance – September 22, 4:00AM EDT (8:00 UTC) - 10:00AM EDT (14:00 UTC)
• EU megaservers for maintenance – September 22, 8:00 UTC (4:00AM EDT) - 14:00 UTC (10:00AM 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.