On Thursday I received a Blackberry 8520 to replace my faulty 8310. The 8520 is a darn lovely phone and an improvement over 8310.
There is no longer the trackball button which is replaced with a trackpad type style of control wish is more responsive and has built in 54g Wi-Fi which one can use to have a wireless broadband connection to your company’s Blackberry Enterprise Server if you use one.
Here is a link to the 8520 specs
http://uk.blackberry.com/devices/blackberrycurve8500/