Oh, the irony.

Oprah gushed about her love of Microsoft’s new tablet computer, the Surface, with the following Tweet yesterday.

A great ringing endorsement by a woman who can actually impact millions of purchase decisions, right?

Well, the message backfired a bit when some sleuths noticed that Oprah actually sent the Tweet using her iPad.

Now, it’s unclear whether Oprah, who boasts 14.8 million followers, maintains her own Twitter account. But, nonetheless, this is not the sort of PR fiasco that Microsoft needs at the moment.

Oprah, you may recall, recently put the Surface on her “Favorite Things 2012″ list, noting that the product “feels like a Mercedes-Benz to me.”

Well, that might be the case. But what “car” does Oprah actually drive?

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