I don't have any of these yet, but I've been hounding the people at work for one.
There are 4 forms of "smartphone" to choose from from Verizon.
Blackberry is the favorite among the business people, emailers, texters - I call them the "thumb-mailers".

There are ways to integrate with Microsoft Exchange servers for enhanced features (all at a price though).
There are the PalmOS units like the Pre. I haven't used a PalmOS unit in ages though.
There are the Windows Mobile phones, that have an interface resembling Microsoft Windows, and may be best for a Windows-centric integration. It may have enough add-on apps for a techie though - I know there is an SSH app that might work for my purposes (logging into remote systems and running commands).
My fave right now is the Android-based phones, which could end up rivaling the iPhone for app availability with an open platform. There are a variety of phones depending what you like for a layout, etc. with the Motorola Droid possibly being the most iPhone-like (not exactly though) but with a full slide out keyboard, which for me means I don't sacrifice screen real estate for a keyboard.
Unfortunately the guy who pays for the phones at work is convinced that the Droid costs way more than some of the others...even though from what I can find the Omnia II (Windows Mobile) a colleague got costs exactly the same, including the data plan...