The webpages for the Update, call it an Update. I guess you didn't read
this:

http://www.palmone.com/us/support/downloads/treo/treo_600_updater.html

but only the SprintPCS link is alive:

http://www.palmone.com/us/support/downloads/treo/treo_600_updater_sprint_
v1_20.html

and it lists the following improvements in the Vresion 1.2 Firmware
Update:

Benefits of the software update include:
=   The palmOne POP3 email client has been incorporated into the Sprint
ROM. The client has been preconfigured for the Sprint PCS POP3 settings.
=   The browser now supports playback of voice memos that might be
received with incoming Picture Mail messages.
=   The browser now supports playback of inline MIDI ringtones.
=   The SMS application now supports Message Priority so that users can
assign high or low priority to all outgoing messages. Additionally, all
incoming messages now display high or low priority.
=   The audio-quality reliability is enhanced.
=   The palmOne car kit now is supported.
=   Browser has been improved to better handle redirect links used in
conjunction with the Sprint download service.
=   Software now reflects the new name of our company - palmOne.

Also nice is that both Windows and Macintosh versions of the updater are
available with full installation instructions.

http://www.palmone.com/us/support/downloads/treo/treo_600_updater_sprint_
v1_20_dl.html

a special caveat is at the side, that I would suggest should have been
made a click through item:

Users of some email or calendar programs, such as PCS Business
Connection, should write down their setup information (passwords,
username, server information, etc.) PRIOR to running this updater. Some
programs do not backup setup information during the HotSync process and
will require you to re-enter this information after the update. If
you're still having trouble getting your email, please contact Sprint or
your wireless email vendor.

They have a troubleshooting FAQ with 9 known issues for updating. OUCH.