Check out PalmOne's latest update file for Sprint Treo 650 1.12

What is the Sprint PCS Treo 650 Updater 1.12?
Enables Bluetooth Dial-Up Networking
Updates VersaMail to version 3.1 to enhance stability and add improvements
Adds support for more Bluetooth carkits including Acura, BMW, Chrysler, Toyota Prius (see all compatible car kits)
Reduces post-dial delay before a call is connected
Send SMS messages from Missed Call Alert or Call Log
Now there's a new user guide that incorporates the changes after running the Treo 650 Updater: Treo 650 User Guide (PDF)
Users are reporting the following improvements:

Keyboard lights now brighten and dim along with the screen.
Digitizer much improved but still not 100%.
More available memory than with 1.08, so they may have improved it further
Dialing is in fact dramatically faster
Also included from the previous version (released March 2005):

Optimizes memory handling and frees up more memory with non-volatile file system improvements (learn more)
Overall voice quality improvements and enhanced call clarity
Internal setting modification to allow correct access to Sprint Affiliate roaming partner networks (previously released as Sprint PCS Treo 650 Roaming Patch)
TTY (also known as TDD or Text Telephone) optimizations and improvements
Optimizations for data calls
Bluetooth Carkit drivers are now included in ROM (previously released as Carkit Update for Treo 650)
Bluetooth Headset Volume Increased
The TreoCentral Staff recommends that anyone upgrading follows the alternate installation instructions.


More info re: Sprint Treo 650 update files