You will need to do get three updates. The plugin itself, Expression Studio 2.5 June release, and the Silverlight Tools for Visual Studio. You can grab all of that here. The updated release of the Silverlight Tools now works with Visual Studio 2008 SP1 beta so you have my official blessing to go ahead and install that too.
In a nutshell, beta 2 has added:
· UI Framework: Beta 2 includes improvements in animation support, error handling and reporting, automation and accessibility support, keyboard input support, and general performance. This release also provides more compatibility between Silverlight and WPF.
· Rich Controls: Beta 2 includes a new templating model called Visual State Manager that allows for easier templating for controls. Other features include the introduction of TabControl, text wrapping and scrollbars for TextBox, and for DataGrid additions include Autosize, Reorder, Sort, performance increases and more. Most controls are now in the runtime instead of packaged with the application.
· Networking Support: Beta 2 includes improved Cross Domain support and security enhancements, upload support for WebClient, and duplex communications (“push” from server to Silverlight client).
· Rich Base Class Library: Beta 2 includes improved threading abilities, LINQ-to-JSON, ADO.NET Data Services support, better support for SOAP, and various other improvements to make networking and data handling easier.
· Deep Zoom: Beta 2 introduces a new XML-based file format for Deep Zoom image tiles, as well as a new MultiScaleTileSource that enables existing tile databases to utilize Deep Zoom. Better, event driven notification for zoom/pan state is another improvement in Silverlight 2 Beta 2.
A lot of the changes you will notice are to keep the Silverlight API in line with WPF. Things have also been simplified a bit. One consistent gotcha I have seen people run into in Beta 1 was when they were calling a Web Service. The need to change their website config file to support basicHttpBinding instead of the default wsHttpBinding (Silverlight only supports basic currently) was often forgotten. There is now a new Silverlight WCF Template that gets installed with the Beta 2 tools that will take care of this for you. Tim Heuer has more info about updated web service changes here.