ASP.NET 3.5 Features

Integrated ASP.NET AJAX support

ListView control - ListView is update to DataList and Repeater controls

DataPager control - Free standing paging Interface. It renders a paging interface with Next Previous first last buttons and is tied to a data web control.
It works only with web controls that implements IPageableItemContainer interface, which currently includes only ListView control

3.5 framework has LINQ - Language Integrated Query.

LINQ makes SQl Like syntax allowing developers to work work with data.
Ex:

List<string> ProductNames = from p in products
where p.productid = 1
select p.productname

LINQ statements operate on Database , XML or an Object Layer.
VS 2008 gives Intellisense support to LINQ Syntax