Windows Phone 7: DOA

Bad news for Microsoft:

Microsoft’s share of the smartphone market is plummeting at an alarming rate–so much so that the company’s last ditch effort to make an impact in mobility, Windows Phone 7, may be irrelevant by the time it manages to ship the much-anticipated Mango update and realize its partnership with Nokia later this year.

Data released Thursday by comScore shows that Microsoft’s average share of the U.S. smartphone OS market over the three months ended in June came in at just 5.8%, down from 7.5% from the three months ended in March, and down from 8% for the three months ended in January.

Microsoft appears to be screwed in the mobile space. WP7 isn’t selling any phones, and putting Windows 7 on tablets is taking too long and a completely boneheaded idea.

iOS runs phones and tablets. Android runs phones and tablets. Windows is… increasingly confined to IT departments as consumers spend their money on post-PC devices.