Confirming rumors that have been circulating for a week, on Monday Apple began inviting the press to a media event for September 9th. As with other media event invitations the company isn't offering details on what will be included, but the image accompanying the event is iPod-themed, with a tagline that reads, "It's rock and roll, but we like it."

Classic-rock music fans will note that the tagline is a variation on a lyric from "It's Only Rock 'N Roll" by The Rolling Stones (off the album of the same name). Many of those same music fans will also know that September 9th is auspicious not just for Apple's long-expected media event, but because it's also the date planned for the release of The Beatles' digitally remastered collection of CDs and the release of The Beatles' Rock Band expansion.

On the surface, one might well expect Apple to use a Beatles lyric for the tagline if this event were to include a Beatles-coming-to-iTunes component, and the additional intrigue supplied by the tagline should manage to generate that much more Internet discussion of what to expect.

As for what to expect, there are three main rumors that have been circulating: The first is that Apple is revamping its iPod line, which seems a gimme considering how Apple has long used a September media event to do just that. Of course, there's also the iPod clutched in the hand of the dancing woman in the accompanying image for the invitation (below).

It's only rock and roll, but we like it."

Secondly, some have expected Apple to use this event to announce a new file format for Albums that includes extra information like liner notes and lyrics. The "rock and roll" tagline lends credence to this idea.

Thirdly, there is the much-rumored tablet that Apple is expected to eventually release as its solution for the netbook market. Unless Apple's dancing model is hiding such a device in her back pocket, however, there's nothing in today's invitation to suggest an iPod super touch is on the menu that day.

Some Wall Street analysts have begun pushing out the date for a tablet device to 2010. If they are correct, that would make a September event too early for a product announcement from Apple, which typically waits until products are ready, or almost ready, to ship before announcing them, especially when it comes to media events where the company controls the timing.

Accordingly, it's a safe bet that the September 9th event, the first since Apple CEO Steve Jobs returned from his 6-month medical leave of absence in late June, will focus on iPod and iTunes-related announcements from the company.

Those in the press who are going, however, can be excused for hoping that Sir Paul McCartney and Ringo Starr will be on hand to play a song to welcome The Beatles to iTunes.

[Update: This article has been updated with additional details. - Editor]