It sounds as if Danger is preparing the first OTA for the Sidekick LX. They are calling the update an “Email Refresh for Sidekick LX Users” and it appears to update your Email application to use tabs, similar to the recently released Myspace application.
Judging from the Screenshots, this looks to make each service you use into it’s own tab. So if you have say your T-Mail account and a Gmail account, there will be a T-Mail and Gmail application to keep them separated. It also looks pretty nice.
No release date information has been specified, and it’s unclear if there will be other fixes or if this just replaces the EMail application.