Essentially inventing the PDA, Palm was an early smartphone pioneer as well. It has suffered years of mismanagement, but Palm continues to offer Treo smartphones with mobile 2.0 capabilities.
Pros: Supports Microsoft Exchange (third-party support for Lotus Notes and Novell GroupWise also available); supports most Web page capabilities; physical keyboard; can view and edit Word and Excel files (and view PowerPoint and PDF files).
Cons: Smallish screen; poor Macintosh support; no Wi-Fi support; limited selection of third-party apps; no built-in RSS reader; awkward Windows-only support for iTunes libraries (via MP3 file transfer on SD cards).