On your iPhone:
Select Settings
Select Mail, Contacts, Calendars
Select Add Account...
Select Other
Name: Your Name
Address: username@exchange.mit.edu
Password: yourpassword
Description: MIT Exchange IMAP (this can be whatever you'd like, it describes the mail account)
Select Save
In the new screen, make sure IMAP is in blue.
Your Name, Address, and Description should of carried over from the previous screen. If not fill in the information.
Under Incoming Mail Server:
Host Name: imap.exchange.mit.edu
User Name: username
Password: yourpassword
Under Outgoing Mail Server:
Host Name: outgoing.mit.edu
User Name: username
Password: yourpassword
Select Save
You may receive a "Secure Connection Failed" prompt, if so click Continue. This is a standard certificate prompt, the connection will still be encrypted via SSL.
Once the iPhone has communicated with the Mail server to verify your settings, you are done. To access your mail, go back to the Home screen and select the Mail icon. 
This year's 3GSM seems to be dominated by announcements of Windows Mobile 6 (WM6) from Microsoft. The new version will now be categorized as Standard (equivalent to Smartphone Edition), Professional (equivalent to Pocket PC Edition), and Classic (non-cellular PDA device with "Pocket PC"). At least eleven manufacturers have announced new devices including new licensees such as LG Electronics, Toshiba, and Lenovo.
Impact on MIT: In the next three to six months, we can expect some of the new devices to be available through US-based carriers. With WM6 features some needed improvements from the previous version, including native support for X.509 certificates, higher-resolution screens (e.g. 320x320 and 800x480), built-in SIP client, etc.
You can find the list of new devices along with external links to obtain more information below:
Windows Mobile 6:
1. Motorola Q gsm & Q q9 (WM6 Standard)
2. Asus Aries (WM6 Standard)
3. i-mate 5150, 6150, 7150, 9150, 8150 (WM6 Standard & Professional)
4. HP iPAQ 510 Voice Messenger (WM6 Standard)
5. Samsung i760 (WM6 Professonal)
6. LG Device (WM6 Professonal)
7. Toshiba G900 (WM6 Professonal)
8. HTC Vox (WM6 Professonal)
9. Lenovo (WM6 Standard & Professional)
10. Palm Treo 750 (WM6 Professional)
11. HTC (WM6 Standard & Professional)
External News Sites Covering 3GSM and Windows Mobile 6:
Engadget mobile: http://www.engadgetmobile.com
CNET: http://news.com.com/3GSM+World+Congress/2009-1035_3-6157682.html