New 21.5-inch Retina 4K models expected.
Mac OS X 10.5.7 Update Improves Battery Life on 'Hackintosh' Netbooks?
Reports from the MSI Wind forums are claiming a boost up to 33%, from 3 hr 45 min to a shade over five hours, using a six-cell 4400 mAh battery.
The writer, Dalton63841, has tested this to make sure its not just over-optimistic reporting by the OS. Another poster is also seeing a boost from three and a half to four and a half hours.
Apple has been rumored to be working on a netbook with a possible release this year.