Apple's annual back-to-school product announcement is guaranteed to set the tech world abuzz, and this year, as always, the air of mystery has fueled the commentators' guessing game. (The only clue is the media invitation, which features a picture of an Apple-branded acoustic guitar.) Here, four informed opinions about what exactly the company will (and won't) reveal during its September 1 press conference:

iPod Touch 4G:
Expect "a new version of Apple’s top-of-the-line iPod" that includes two cameras, one front-facing, says Brian Caulfield in Fortune. This model will be "more like an iPhone" than previous incarnations, and may well offer a high-resolution "retina" display and the ability "to place calls using Apple's FaceTime video calling technology." Apple, says Erica Ogg in CNet, traditionally releases new iPod hardware in September, so this rumor seems like a sure bet.

Updated iTunes:
Many have speculated that Apple has finally gained the rights to release the Beatles' catalog on iTunes, says MG Siegler in TechCrunch, but you "probably shouldn’t count on it." More likely, says Peter Kafka in All Things D, the company will announce a new "lightweight, web-based version of the iTunes store" that "would be designed to sync up easily with the rest of the internet and make it much easier for customers to share their musical tastes (but not songs) with friends."

99-cent TV shows
Tim Gideon in PC Magazine is high on a New York Times report indicating that Apple plans to launch a television show rental service that will charge users just 99 cents per episode. Rumor has it, he says, that this "is going to happen" and it's a welcome idea: The current TV downloads on iTunes are "a bit pricier than most people want to pay."

Apple TV
While a number of news outlets have reported that Apple will reveal a revamped, $99 version of the Apple TV set-top box, some industry experts are dubious. This event will "be about the iPod," market analyst Brian Marshall tells Reuters.