I think you misunderstood the Joel test. Joel test is not about products, languages and technologies used. It's about the workflow and the working conditions of the developers.
For example, the five points in user8685's answer has nothing to do with Joel test. It's not because the company's website is not written in valid XHTML that their developers have no decent working conditions.
The difference may be subtle, but there is a difference. For example in a company working with .NET technologies, it doesn't matter if it's Visual Basic or C# or F#. It's not a working condition¹. What matters is that some companies will let you work with Visual Studio 2010 Ultimate installed on quad-core machines connected to 100 Mbps internet connection, while in other companies you will have to work on old garbage running Windows Millenium, with Visual Studio 2003 installed on one computer, and just a notepad on ten others, because VS is too expensive.
Taking the three points you quoted:
1 Do you use source control? (source control for all aspects of your app, including configuration, database and user-based settings)
What's so special about web applications ? You do have configuration in desktop applications too. You do have database and you do have user-based settings.
By the way, you do have to use version control for your database like you use source control for the source code.
2 Can you make a build in one step? (can you deploy a site from staging to prod in 1 step)
It's not because a company let their developers deploy a website from staging to production in one step that this company is better then other ones. Facebook does it. Dell does not. IMO, developers must not be trusted enough to be able to alter the production website directly.
Also, build in one step concerns the build itself, not the fact to push a website from staging to production. Website builds are very similar to desktop application builds.
10 Do you have testers? (how do you test ajax and CSS?)
How do you test desktop application UI ?
¹ I must however note that for some developers, a choice of some languages can actually be a working condition by itself (think PHP, COBOL, etc.). For example, it is depressing for me to use PHP on daily basis, exactly like not having two/three monitors per PC or not having quite working conditions or having 128 Kbps internet connection.