From All About Symbian:
Nokia Messaging 10.2 and Mail for Exchange have just been pushed out for Nokia’s 5800 XpressMusic, 5530 and X6-00. These updates are over-the-air (OTA), and should be available via the Software Update application. Nokia Messaging provides push email to these handsets via Nokia’s own push mail service from popular services like Ovi Mail, Gmail, Yahoo Mail, etc. Alongside the Nokia Messaging update, Mail for Exchange has been added to these handsets providing push email and PIM push synchronisation with corporate networks, and third party services like Nuevasync.
If you’ve got any of these devices, check the SW Update app on your phone to see if its ready for you to download yet.