Traditionally, the next version or major release of Windows Operating System should appear nearly after after 3 years of Windows 7 i.e. 2012. This is further being ensured by a recent road map. According to this road map, there will be a Major Windows release in 2012. Note that it is a Major Release in their words. This depicts that the users will get a completely overhauled version codenamed Windows 8. We are expecting a major overhaul because this road map considers Windows 7 a release update.
The recent job postings are also major indications that Windows 8 development is on rise. It is likely that Redmond Giant will get more focused on Windows 8 development as the fiscal year 2011 starts around July 2010. These job postings also point to some salient features of Windows 8. Now we should expect release date of Windows 8.
Update 1: There has been some sort of official leak regarding release date of Windows 8.