Trying to do the Opera Mini one better is the new Skyfire browser. Like the Opera Mini, Skyfire works by combining an on-device browser with a middle-tier proxy server that compresses and optimizes normal Web pages for delivery to the mobile browser. Skyfire’s big point of differentiation is that it also handles Flash content – which both the iPhone and Opera Mini browsers do not – which means that Ajax or Flash-heavy Web sites such as YouTube or ESPN.com look largely the same in Skyfire as they do in a desktop browser.

Skyfire launched this week at the Demo Conference, with the browser available today only as a private, invitation-only beta. The beta version works with Windows Mobile phones. The company announced plans to introduce a version for Symbian smartphones and other platforms in coming months.

Also this week, the Mozilla Foundation showed the first prototypes of Firefox Mobile, which it announced last fall. The group posted two prototype user interfaces and a reference implementation on the Mozilla Wiki. One of the prototypes is for touch-screen devices; one for button-based ones. The user interfaces are built using XML User Interface Language, or XUL, and page rendering is handled by Mozilla’s Gecko engine, the same as on the desktop. The mobile prototype browsers feature scrolling, zooming and panning – much like the iPhone or Opera Mini.

“We’re leveraging the same code base as desktop Firefox; we’re basically working to make the standard Firefox browser work on mobile phones, said Christian Sejersen, director of engineering for Mobile Firefox and formerly head of the engineering effort at OpenWave Systems, a pioneer in mobile application software. Sejersen said Firefox Mobile assumes all page rendering will be done on the phone, but the group “hasn’t ruled out” using a proxy solution that might sit between the Web and the browser.

One area that the group wants to keep consistent between the desktop and mobile browsers is the ability to use extensions to augment the core browser’s capabilities – including an extension that will enable Flash playback within the client, added Jay Sullivan, senior director of Mozilla Labs.

“The ability to use extensions gives us quite a lot as we look to improve the performance and experience of using Firefox Mobile, Sullivan said. “Extensions are one of the things that make Firefox great. It will be an interesting area for [mobile] application developers as well.”

Mozilla is aiming to deliver the first working version of Firefox Mobile by the end of 2008, the group said.

“There’s still a lot of work on mobile browsers to be done,” Sullivan said. “The iPhone, Windows Mobile, Android are all still works in progress. Nobody has a final, perfect solution yet.”