We have been long time WM6, Palm and recently iPhone users. Depending on your business requirements, you'll likely find it's going to be a tossup between WM6/7 (if you want to wait), Blackberry and iPhone. For our business, users find the slow, graphically outdated and unnecessarily complex UI on WM6 to be unacceptable. Palm was the preferred platform for its stability, performance and graphical superiority at one time. The iPhone is the new king of UI, while it lacks severely in the functionality and enterprise control areas. Blackberry works well in large corporate environments wanting complete control over the device.
Here's a question: what about the sites devoted to dishing on companies by anonymous (current or former) employees? Glassdoor.com is a perfect example. People submit either or both salary info and pretty detailed reviews of working at a particular organization--down to who was the president while you worked there. Can IT control what people do anonymously (and sometimes on their own time?)
Anonymous submissions on sites such as glassdoor.com allow for freedom of expression and act as a watchdog for perspective employees so they can gain insights into company culture beyond the "about us", and HR information they may receive from the company website.
Companies should ensure their culture is conducive to productive employee behavior, which should improve their reputation on sites such as glassdoor.
The analogy that comes to mind is of Amazon and Ebay reviews where customers can leave feedback on product purchased and their experience with the transaction from initiation to final delivery.
I do see an increasing trend of medium and large companies permitting employees to use social networks at the office. Two years ago many organizations banned employees from participating, but more are relaxing these constraints. Some are seeing value and the SN and encourage employees to participate in SN and public forums that speak about their products and services. It can help to get the word out.