Logged into the Sprint PCS web site to check my SMS'es because I couldn't find my Treo. On going to the SMS section, I get this:

Messaging Alert
Sprint will discontinue the View and Organize feature for One-Way Messaging and Short Mail from this website beginning on or after the 17th of November.

These changes will not affect your Sprint Phone functionality. Short Mail messages are still accessible from your phone's web browser and any text messages/notifications stored on your phone will not be affected.
How do I find my Short Mail Messages on my phone?
I remembered that Treo300SMS from PDAApps, at the time that I bought it, said it used the website's gateway.

The PDAapps SMS proxy system depends on the Sprint PCS text messaging web site to send your shortmail messages to your phone as text messages. If you are unable to access this website for any reason (e.g. it is down for maintainance), you will not be able to receive your SMS messages
Does this mean Treo300SMS has a month to live?

-Alex