NEW YORK (AP) — Apple is holding an event today in San Francisco, and has hinted that it will reveal a new iPad model. Rumors speak of an updated tablet with a speedier processor, a sharper screen and an option for faster wireless broadband access.

If last year’s launch of the iPad 2 is any guide, the new iPad model will go on sale in the U.S. next week, likely on Friday.

The upgrade from the iPad 2 to the iPad 3 will be less significant than the upgrade from the original iPad to the iPad 2, which added two cameras while cutting both the thickness and the weight of the device.

One big unknown is whether Apple will keep the iPad 2 in production and offer it at a lower price, like it kept the iPhone 3GS after the launch of the iPhone 4.

Another big question is whether Apple will reveal its rumored foray into making TV sets. Some have speculated that the invite to the Apple event, which said “We have something you really have to see,” points in that direction.

Apple already sells an “Apple TV.” It’s not a TV, but a small box that attaches to a television set to display movies and play music from iTunes.

The iPad launch comes as Apple has reached a rare milestone: Last week, it was worth more than $500 billion. Only six other U.S. companies have been worth that much, and none have held that valuation for long. On Tuesday, Apple’s stock fell, bringing its market value down to $493 billion, but analysts believe the company is worth closer to $550 billion.

These are some rumored features of the iPad 3:

— A sharper screen, similar to the “Retina Display” on the iPhone 4 and 4s. The rumored resolution is 2048 by 1536 pixels, which would make text look smoother and some high-resolution pictures look better. It won’t make much of a difference for images on the Web, or video.

Some speculate that Apple will call the model the “iPad HD,” for “high definition,” rather than “iPad 3.”

— The new iPad could include Siri, the voice- activated “ assistant” found on the iPhone 4S. Siri has gotten mixed reviews, but Apple has been touting the feature heavily in its advertising, and it would make sense to expand the availability of this high-profile feature.

— Faster wireless capabilities.