While the Service Pack is mostly focused on improvements in response to feedback on Visual Studio 2010, one new feature I want to highlight is the integration of IIS Express into Visual Studio 2010. IIS Express, which was introduced with the new Microsoft WebMatrix editor, is a lightweight, yet full-featured version of IIS that can run without administrative permissions, allowing you to develop and test full-fidelity sites in scenarios where the full IIS 7.x would be impossible, such as where policy prevents installation of IIS, or on Windows XP.
This is a BIG win for developers, since it means that no longer do you have to wonder whether your site will continue to work once deployed, whether you’re using SSL, or HTTP compression, the features you rely on will be there for you in IIS Express.
So go grab the Service Pack, and get coding! And check out Soma’s blog for more details on what other improvements are coming along with SP1.