Here's a consolidated list of all the key downloads you'll need to update your developer workstation to the latest and greatest technologies announced this morning:
A couple of tips:
Have fun!
OK, so you've got all the bits downloaded and installed on your machine. What's the best way to start
Is the MVC preview you have linked a subset of the ASP.NET Extensions refresh?
It's separate, I believe. Tim
Tim Sneath has a great summary of links the technologies we announced at the MIX08 keynote this morning. 
This morning during the key note @ Mix, Microsoft announced that Silverlight 2 Beta 1,  Expression
Just to add, as announced during the keynote, the source code to the managed Silverlight 2 controls and unit tests are also available in a separate download at http://www.microsoft.com/downloads/details.aspx?FamilyId=EA93DD89-3AF2-4ACB-9CF4-BFE01B3F02D4&displaylang=en
If you're thinking about cracking on with Silverlight - then here's the place to start. This
Did anyone else have the install of the "Tools for VS2008" prompt for the Visual Studio 2008 install disc?
I thought this was weird.
Fortunately I had a retail disc handy and stuck it in to complete the install. The “browse button” was looking for vs_setup.msi. I assume that this was the original install file.
If you installed VS from the web or a share, you might want to locate it before you begin the install in case you run into the same problem I did.
Expression Blend 2.5 still has some issues when working with Globaized applications
Скачиваем и устанавливаем: http://blogs.msdn.com/tims/archive/2008/03/05/download-links-for-mix08-announcements.aspx
So we have both "Expression Studio 2 Beta (contains Blend, Design, Encoder, Media and Web)" and also "Expression Blend 2.5 March 2008 Preview"
Can we install both of these? Or should we select just one version of Blend?
Hi Ian, we aim to confuse :)
Here's the deal. Moving forward, Expression Blend 2 contains support for shipping technology: that is, WPF 3.x and Silverlight 1.0. Expression Blend 2.5 is a preview of the next release after Blend 2; it runs side-by-side with Blend 2 and supports WPF 3.x, Silverlight 1.0 and Silverlight 2. You're probably best to install both together - at this point, Blend 2 is more stable than 2.5 as a development environment for WPF and Silverlight 1.0, according to my Blend buddies.
Hope this helps, Tim
I've updated the links above to also include the source code for the controls and unit tests. Thanks, Jeff!