The subject of rumors for nearly a year, Apple today is expected to release the details of its new iPad at 10 a.m. PT. As usual, the company is tight-lipped, but as the date approached, the usually credible sites' rumors have converged to a description of a new iPad that appears to be an incremental update to the very popular iPad 2.

The tablet, called the "iPad 3" and "iPad HD" by rumor sites, is likely to have a Retina display, meaning four times the pixels of the original iPad and iPad 2 in an array of 2,048 by 1,536 rather than 1,024 by 768 on the same 10-inch screen. As in the case of the iPhone 4, which added the high-density Retina display nearly two years ago, the higher resolution does not mean more pixels packed into the same space but higher-definition pixels composed of four subpixels; that density approaches what the human eye sees as a continuous tone. (Doubling the addressable pixels would just shrink everything to half size, which would make the iPad's screen impossible to read.)

It's also highly likely that the "iPad 3" will pack a faster Apple A5 CPU and graphics coprocessor to handle the greater number of pixels to display and refresh. Such a faster processor, when combined with the same noise-canceling circuitry that debuted in the iPhone 4S, would also allow the "iPad 3" to run Apple's Siri voice-based personal-assistant technology -- a feature the iPad 3 is widely reported to have.

Possible but not as likely is support for the LTE 4G radio technology that Verizon Wireless and, to a lesser extent, AT&T have been introducing to some U.S. cities in the last year. LTE support is common on newer Android devices, but it's also a big battery drain on many, and LTE speeds have not consistently outperformed standard 3G networks. Still, it's been reported by several often-correct websites that the "iPad 3" is slightly thicker (by 0.8 millimeters) to accommodate extra batteries to support the LTE-capable radio without compromising the iPad's 10-hour battery life. Still, it's possible Apple may skip LTE in this version, given its low deployment in the United States and nearly nonexistent availability elsewhere in the world.

Beyond these widely expected changes, what else Apple may have up its sleeves for the "iPad 3" is unclear. Many people hope for a higher-resolution camera to match that in the iPhone 4S, but smartphones such as the iPhone are natural camera replacements whereas tablets are not. Apple has previously justified the iPad 2's (relatively) inferior camera, claiming its primary use is for Apple's FaceTime video chat service.

Beyond the "iPad 3," Apple is widely expected to announce it will keep the popular iPad 2 but sell it for a lower price, much as it has kept both the iPhone 4 and iPhone 3GS after the iPhone 4S's debut. A revamped Apple TV is also expected today or in the next few weeks that would boast a faster processor to support AirPlay streaming of the higher-definition video supported by the "iPad 3" Retina display.

Apple no doubt has a surprise or two that it's managed to keep secret, perhaps related to new capabilities in iOS 5.1, the App Store, or media services.