Geekiest.net using BlogEngine.Net, which is an open source blogging software written in C#. and also it does not need a database (it can use XML to store the data). Also it supports MSSQL, MySql etc too.
Yesterday BlogEngine released its Version 2.0. Latest version changes are
1. Upgraded .net framework to 3.5
2. Control panel is totally new
3. Captcha (Recaptcha and simple captcha)
4. Can use Disques for commenting.
5. SQL CE 4.0 support
6. Recycle bin for Posts, Pages and Comments
7. Security improvements – related to external content the blog may download
8. Private blog feature – require users to be logged in to access the blog
9. Option to allow self-registration for visitors
10. Support for Unicode characters in the URL for Posts and Pages.
If you are already using a blogengine.net for your blog, you can read the upgrade instructions here