Two new updates have been released for owners of newly released iMacs.
iMac SMC Firmware Update 1.1 (921KB)
This update is recommended for new iMacs (late 2013) that have flash storage only. It improves the Power Nap functionality in OS X Mavericks, making everything work without the fan running. See more information about Power Nap in this post.
iMac 10.8.5 Supplemental Update 1.0 (17.1MB)
This update, also for iMacs (late 2013) but equipped with the NVIDIA GeForce GT 750M graphics card and running OS X Mountain Lion 10.8.5, fixes two problems: one that could eject external drives after the computer went into sleep mode (sleep) and another that prevented certain Bluetooth USB adapters from working properly.
· · ·
The updates are available through both the Apple website and Software Update (Software Update) built into the system.