Microsoft has announced that more than 55,000 projects have been created using the Windows Phone App Studio beta, a tool that allows you to build and prototype Windows Phone apps in the browser. In order to help manage demand Microsoft instituted a temporary access code system, shortly after the tool went live, which requires you to send an email to get an invite code (usually delivered within a few minutes).

The tool has also been updated today adding support for Flickr photo feeds to be used as a data source, new templates (video channels, country side, birthday party, my hero, my diet, my city), and making some underlying changes to improve overall performance and stability.

The number of projects created using the online tool is impressive. 55,000 is roughly on third of the amount of active apps in the Windows Phone Store. Clearly only a tiny fraction of apps created using Windows Phone Studio will ever be published to the Windows Phone Store, but it does suggest there's strong latent demand for a tool that allows people to create their own rich content presentation experiences for thier smartphone.

Microsoft says that Windows Phone App Studio has attracted two types of users. Firstly people creating personal and specialised apps for specific needs that they share with their family and friend:

We’re getting feedback from users that they really like creating apps on their own terms. Apps created in App Studio don't automatically publish to the Windows Phone Store or raise the number of apps available to everyone, and we’re fine with that; it’s great to see hobbyists and non-professional developers using these tools to create apps for personal use. If and when they’re ready to offer their apps more broadly, it’s easy to take the next step to open a Dev Center account and submit their apps to be published in Windows Phone Store.

Secondly professional developers are also using the tool, taking the output and customising it using Visual Studio:

We’re finding that professional developers have begun using the tool as well. One of these is developer Rob Miles, who is documenting his experience importing App Studio code into Visual Studio to create a custom app that he can submit to publish in the Store.

More on the Windows Phone Developer Blog here.