Earlier this month NVIDIA released the first 280 series Linux driver
with initial support for X.Org Server 1.11, among other changes. Before ending out last week, NVIDIA's engineers released another 280 beta Linux driver.
The new driver is the 280.11 release, but it's not particularly exciting. The only official change to this driver is fixing a GLX_EXT_texture_from_pixmap bug that caused regressions with small pixmaps, such as those from the GNOME Shell Message Tray. Given that it's been about three weeks since releasing the initial 280.04 beta driver, there's also likely other fixes and improvements encompassed by this 280.11 update, but that's all NVIDIA has publicly acknowledged.
Download links for Linux x86 and x86_64 for NVIDIA's proprietary driver beta can be found in this forum thread