Yahoo! yesterday announced it will run a new class of interactive mobile display advertisements that leverage HTML5, CSS3 and Javascript to deliver “more engaging experiences” for advertisers and users.

In a blog post, the company described how mobile display ads generally take the form of static banners across the top and bottom of the screen. But engaging mobile users has been challenging.

“With advancements in smartphone technology and the next generation of HTML5 browsers, it is now possible to display highly engaging and interactive Rich Media content on high-end mobile devices,” the company said.

Yahoo! is showing off its first campaign developed in collaboration with Paramount and DreamWorks Animation for the release of Shrek Forever After, which (in case you haven’t heard) opens May 21.

Meanwhile, Yahoo! CEO Carol Bartz is hosting a press conference in New York on Monday. Details were short, with a press invite says she will discuss something about “providing global consumers with rich online and mobile experiences and bringing forward a new era in keeping consumers connected.”

All Things Digital’s Kara Swisher cites sources saying it will be about a deal with Nokia to build Yahoo email, search and other applications and services into a range of devices.