Microsoft did not come out with a new release of IEWC for asp.net 2.0. Rather, the controls have been brought into asp.net 2.0.
For example, a treeview is offered "out-of-the-box". The interface is different from the IEWC treeview, e.g. you don't have to know xslt to use an external xml data source. And you can't just convert your IEWC app to an asp.net 2.0-without-IEWC app, but the changes can be straightforward, particularly with intellisense.
But if you're too busy to update an app developed with IEWC, it should run fine under asp.net 2.0.