Blue would not only be the codename for a large update for Windows 8 but also a large update for Windows Phone, Windows Server, Hotmail and Skydrive. Microsoft will update its products every year from now on, according to ZDNet.
The Blue update would be the first time that Microsoft will update a large amount of its products at once. ZDNet claims that the information comes from a reliable source close to Microsoft. The site frequently receives correct insider information about Microsoft which makes the rumor trustworthy. The site was also the first to report about the existence of the Blue update.
If the information is indeed correct, it's the first time that information becomes available on a large update for Windows Phone 8. The mobile operating system already received an updated called Portico, but this was rather small and mainly fixed some bugs. A large update hasn't been announced, but could now be part of the Blue release.
Besides the large yearly updates that should be released at once, it's likely that Microsoft will also release smaller updates more often. Release dates for these updates would vary per platform. The yearly update cycle isn't new for Microsoft but other large tech companies use the same method. Apple releases a new version of iOS and Mac OS X every year and Google releases large updates for Android at least two times a year. Canonical also releases two updates of Linux variant Ubuntu.
In the meantime development of Windows 9 also seems to have started. ZDnet has posted a picture of a Linkedin profile (now changed) that reveals that Microsoft has developers in India working the successor of Windows 8.
