No. I work for a small subsidiary of a large engineering conglomerate. Most of the parent and other companies are going blackberry, but I find them somewhat limitting and expensive. The way our security is set up makes the Treo a tough one. I'd only be able to get to email via an html interface or some yet-to-be-determined sych software.
The PPC route has a client for our VPN (SecureClient) though I hear it can be flakey.
Anyway, main use is email, calendar, a bit of word/excel and web browsing.