BES and WebClient

There are two types of services for the Nextel Blackberry (as well as other carriers):  BES and Web Client

BES (Blackberry Enterprise Server) is aimed for corporate use.  Having BES will unleash the full potential of the Blackberry.  Services include a full HTML browser and wireless synching with Outlook and other corporate software such as Lotus and Act.  Emails are also handled from the BES server side and can support multiple pop3 accounts.  BES users are at the dispnse of corporate IT guys who run the servers and have control over the BB user's access.  A typical BES setup would run you close to $10,000 +.  There are third party BES services available for a monthly charge.

Web Client is what the consumer BB market uses and is what I have.  It supports only one email account (your_.blackberry.net account) and requires third party browsers such as ReqWireless WebViewer for HTML browsing.  May 16th is the anticipated date that Nextel will roll out a full HTML browser for web client which would make it more on par with BES users.  And because WebClient is aimed for individual consumers, you have more control over what you want to do with your BB.

For more defintions, here's a great source: Blackberry glossary.