The Chief Administrative Office (CAO) oversees all communications systems for the House and has been testing a small number of iPhones to see how they meet the needs of congressmen and their staffs.
House members and their staffs currently use RIM BlackBerry devices, with nearly 8,200 installed. The CAO delivers all emails to the BlackBerrys using a BlackBerry Enterprise Server. A new server would be required for the iPhones, so the CAO wants to test the devices and email delivery prior to making a decision to approve use of iPhones.
The CAO is testing iPhones simply because a number of people had requested them as an option. If the CAO does approve the iPhone and lawmakers decide to switch, they'll pay for the devices out of their Member's Representational Allowance (i.e., taxpayers will be paying for them).
Adoption of the iPhone by the U.S. Congress could be another blow to RIM, which is now behind Apple in terms of sales and revenues. Apple CEO Steve Jobs gleefully reported that "Apple beat RIM" during yesterday's Q4 Earnings Call.
Thanks to Kyle for the tip!
Update: Jordan Golson points out TheHill.com got this story all wrong.