Since my company uses GroupWise and hasn't yet rolled out the new GroupWise Mobile Server module I have a hosted Exchange account for all my blog and website email, calendar, and contact information. The hosted Exchange solution from 4Smartphone has been very good and I love the push email functionality I get on my Windows Mobile and Nokia E61 devices. The push email functionality originated with RIM BlackBerry devices and larger companies with a BlackBerry Enterprise Server can provide that to employees. However, it isn't very economical for small businesses to get hooked up to a BES so they generally had to look for another 3rd party solution. RIM announced a new Hosted BES that allows service providers to offer hosted services. The Hosted BlackBerry Enterprise Server is a new software application that adds all the BlackBerry functionality for small and medium sized businesses.
You will need to check with your wireless carrier to see if a hosted solution is provided. The Hosted BES supports integration with MS Exchange, IBM Lotus Domino, and Novell GroupWise. For some reason I always thought this was provided by carriers like T-Mobile, but after further digging around I see that you still need a corporate BlackBerry Enterprise Server even with a device and service from wireless carriers. I think this new Hosted BES solution will benefit both carriers and users who want the BlackBerry experience, but don't want to use a Windows Mobile or S60 Smartphone device with hosted Exchange. I could not find any carriers or other providers currently offering these services so we will have to wait and see who picks it up and what the costs will be for users.