There's lots of Open Source apps like Blogs (like DasBlog, that runs this site!), Content Management Systems (like Umbraco, that powers !) and other apps that you can start working with immediately. These are regular ASP.NET and PHP apps that you've probably used before. You can install a site from the Gallery, like ScottGu did when he chose BlogEngine.NET. The WebMatrix download for me was 8megs, then SQL Compact was 2.5megs, and then some deployment dependencies brought my total download to 29 megs. It'll install the Web Platform Install (about 2 megs) and then you click Install. Go to the WebMatrix site and click Download Now.

Here's how you'd get WebMatrix, sign up for a new host, and deploy your first site. However, folks that are starting out, or hobbyists, or maybe just installing a blog or forum will use WebMatrix to get stuff done. Pros will like a free file-based SQL Server, and a non-service version of IIS that's more compatible than the Visual Web Developer, and pros might like using Razor as an alternative View Engine for their ASP.NET MVC sites. This isn't for professionals, even though it has components that professionals will use. I tried to get my wife, then later my 10 year old nephew to make a website and it was a non-starter. Visual Studio 2010 looks like a dashboard. I've said before that Microsoft is just now starting to get the 'right-sized LEGO pieces.' It the past some stuff was too little or too big, but now as an example, here's five separate and right-sized LEGOs (ya, I know it's singular) that are helpful for the professional and the folks just getting starter, or those who don't want to learn a bunch of stuff to setup and/or modify a website. It'll make recommendations and store reports.

WebMatrix also has the Search Engine Optimization Toolkit built in, so you can spider your own site and see how Search Engines see it.

It uses the WebDeploy engine to deploy apps to hosts, setting up permissions, copying databases, etc.

It's a simple syntax that is easy to learn

It uses a View Engine called 'Razor' to make Web Pages, and your sites can be later be expanded to use all of ASP.NET MVC.

It has a small embedded file-based SQL Database, and a web-server called IIS Express that's compatible with the full version of IIS.

NET 4, 50megs if you don't) lightweight IDE for making ASP.NET or PHP websites. ScottGu announced Microsoft WebMatrix Beta today.

Microsoft webmatrix beta