MSDN recently rolled out new presentation choices for its Library content, which includes the MSDN online section for Silverlight:
If you haven't been there recently here's your obligatory handy link: Silverlight 3 on MSDN
The added presentation choices are a Lightweight view and a Script-Free view. To change the views, click the orange, docked Switch View button. With a switched view, you may notice that you'll have an additional qualifier string in the address bar that shows you the MSDN URL, for example: http://msdn.microsoft.com/en-us/library/cc838158(VS.95,classic).aspx although your view is also potentially session-preserved without that necessarily being in the URL.
The MSDN redesign was originally announced by Soma on Oct 19th. You can learn more about the redesign by following links from that post.
Probably the most immediately observable difference in the presentations is how the Table of Contents (TOC) is treated. In Classic view the TOC remains fully expanded for context. In Lightweight and Script-Free views, the TOC filters down to showing immediate peer topics, and does not show expansion and the set of peers that exist at each decision point as you "walked" the TOC to get to the current page. Depending on your connection speed, Lightweight can potentially help pageload time. The TOC in Classic does a lot of scripting and downloaded pieces, and synching the TOC might be slowing down your pageloads. On the other hand, the full context of the TOC can be nice to see. Not all who wander are lost, right?
I'd be interested in knowing what the Silverlight developer audience thinks of the redesign, and which view this audience prefers. The SDK team often holds the superstition that a Silverlight developer audience uses MSDN more than any offline documentation source, since Silverlight is a Web technology and MSDN is ... on the Web. Plus Silverlight inherently touches on a lot of issues of onscreen design and UI usability. If that's so, then I'd expect Silverlight developers to be even more willing to share their opinion.
Maybe it's just me, but the concept of "Classic versus Lightweight" makes me think of Charles Atlas. :-)