In a note to clients Wednesday, Gene Munster put his spin on recent rumors regarding the Apple (AAPL) tablet computer that nobody has seen but everybody is talking about.

• Acknowledging media reports — including one in the current Financial Times — of an Apple announcement in January, Munster puts the odds of a special event occurring at 75% and the odds of a tablet being announced at that time at 50%.
• If the tablet were announced in January, he would expect it to ship some time in Apple’s second fiscal quarter. “Based on a conversation this week with a Taiwanese component supplier,” he writes, “we expect Apple to ship a tablet device by the end March.”
• Munster had previously estimated a monthly run rate of 162,000 units once the tablet ships (about 2 million annually). “Assuming the tablet comes out in [March],” he writes, “we believe Apple would sell around 1.4 [million] units at a $600 ASP in [calendar year 2010], an increase of about 2% to revenue.”
• Other reasons Apple might hold a January event: to launch a new iPod touch with a video camera, or a new Apple TV that could support a subscription TV service (see Can Steve Jobs unplug cable TV?)

What does Munster expect the tablet to be like? Read on:

“We expect the tablet hardware to be similar to an iPod touch but larger (about 10″); we expect the key differentiator of the device to be its software. While there are several options ranging from a touch screen Mac OS X to an iPhone-like OS, we expect the tablet to be driven by a new version of Apple’s iPhone OS that runs a new category of larger apps alongside all the current apps from the App Store. We believe Apple’s tablet would compete well in the netbook category even though it would not be a netbook. Rather it would focus more on apps, entertainment content (from the iTunes Store), and web surfing.”

Meanwhile, the Boy Genius passes along a rumor that there is “definitely” a 7-inch model being introduced in January. “Whether this is in addition to a 10″ model, [his sources] don’t know.”

For various artists’ renditions of the mythical tablet, see Silicon Alley Insider’s gallery here.

See also:

• Apple tablet set for spring launch?

[Follow Philip Elmer-DeWitt on Twitter @philiped]