A Friday report from Bloomberg suggests that Microsoft will not launch a tablet version of Windows until the late summer or early fall of 2012.

The report builds off a few Windows 8 and tablet rumors that have been building past weeks. Late last month, ZDNet’s Mary Jo Foley published a screen shot she received from a source that showed Microsoft should be on track with its second milestone for developing its latest platform, putting it on track for its third milestone and a planned September 2011 release .

On Tuesday, Business Insider reported that the company is planning to show design demos of Windows 8 on tablets by the end of its fiscal year in June. The design is said to be based on a more “Apple-like” interface design and concepts from a 2004 interface called “Metro.” That article also pointed out that if Foley’s screenshot is correct, the company is following the same steps it did with the Windows 7 release with a public preview a year before the official release date.

All these reports cite the usual (somewhat cloak and dagger) “people with knowledge of the plans” or other anonymous sources who declined to be identified, but the rumor mills all seem to be churning in the same direction.

The real question here is whether waiting until 2012 to release a tablet Windows OS is soon enough to compete with whatever Apple and Google’s Android have cooked up by then. Apple CEO has said 2011 is the year of the tablet (well, specifically the post-PC or iPad 2), so will a 2012 offering be soon enough for Microsoft?

What do you think? Is Microsoft waiting too long to take a jump into the tablet market?