Fastmac, who know how to make iPhone backup chargers, just made a more form-fitting version that also has an IR port. That means your iPhone is now a universal remote.
With their included app, the iPhone 3G and 3GS can control basically any IR-sensitive device you have as long as it's docked into the case. The case itself has a 1300 mAh battery, a built-in flash, a USB port for charging another device, and an on-off toggle. The price is $100, which is slightly higher than normal cases, but normal cases can't turn your TV on and off. It also has neat functions like being aware of your local channel guide and jumping to the correct channel, like a real grown-up universal remote.
No solid word on availability yet. [Fastmac]
Update: Looks like the remote software is made by UMEE, so we're looking forward to seeing what they do with it.