Autonomic Controls has released an application that lets Windows CE-based PDAs or Windows-powered UMPCs (ultra-mobile PCs) control Windows Media Center PCs remotely. Unlike infrared remotes, however, the company's "Mirage" software offers two-way communications with the media server.
Written in Macromedia Flash, Mirage reportedly can run either within a Web browser or as a full-screen application. The latter mode permits full touchscreen operation on the handheld device.
Mirage, running on the handheld device, works in conjunction with a PC running Window XP Media Center Edition 2005 with Update Rollup 2, or one of the two editions of Windows Vista that include Media Center: Vista Home Premium or Vista Ultimate.

Downloadable here in a beta version, Mirage will run free for 14 days before licensing is required.