I'm quite sure I've seen them somewhere in the request before, but I think only if using the MDS/BES.
Each BlackBerry Browser user can also be uniquely identified. A BlackBerry® Mobile Data Service administrator can configure a BlackBerry Mobile Data Service server to send a BlackBerry smartphone userxxx8217;s email address and personal identification number (PIN) with each Hypertext Transfer Protocol (HTTP) request from a BlackBerry Browser. The BlackBerry Mobile Data Service can also be configured to send this information to a certain domain, such as a corporate intranet. If configured, the email address and PIN are sent as headers in the HTTP request and appear as follows:
Note: The Rim-device-email and Rim-device-id parameters can only be sent when using the BlackBerry Browser, and are not available when using the WAP or the BlackBerry® Internet Service Browser.