No one's sure what Apple will announce today, but the folks at Bookmaker.com just weighed in with their take. As for the unveiling of Apple product upgrades for the upcoming holiday season, the event is invitation-only, and the invite has only a picture of a guitar as a clue.

That hasn't stopped people from speculating, of course. Piercing Apple's shroud of secrecymdash;or at least guessing what's behind the curtainmdash;has become a full-time job for many, from bloggers to Bookmaker.com.

Here are Bookmaker's odds of what will be announced later today:

  • 50 per cent chance of a revised version of the iPhone 4
  • 40 per cent chance of a new iPod nano with 3 centimeter by 3 centimeter touch screen
  • 33 per cent chance of an Apple TV priced at $99
  • 28 per cent chance of a new iPod touch

Bookmaker.com calculated these odds by analysing media reports and expert opinions being published on the topic.

The most surprising piece of Bookmaker.com's odds is the low odds for a new iPod touch. Some mainstream media outlets are predicting an iPod touch refresh.

Apple

"Apple is expected to show a new iPod touch with a camera for video chatting," writes Ryan Kim, staff writer at the San Francisco Chronicle. He also figures Apple TV set-top box will get a refresh and resemble iPhone 4 with Apple's mobile iOS.

Analyst Rob Enderle doesn't think an iPod touch makes much sense in today's always-connected, location-based app world, which is why Apple focuses on the iPhone. "We are just short of having the low cost, ubiquitous broadband connection that devices like [the iPod touch] require," he says. "Until we get that kind of service, the iPhone and its contemporaries are likely the best choice."