I'm slowly converting a number of blogs from Blogger to BlogEngine.NET. The least fun part is dealing with the Blogger export file. For this blog I used a Powershell script but had problems with comments not exporting correctly and it was quite painful to fix everything up. Blogger allows you to export a copy of your blog using ATOM, however BlogEngine.NET (and other tools) speak BlogML.
I've just released a command line tool that takes the ATOM format Blogger export and converts it to BlogML. You can download Blogger2BlogML from Codeplex. The tool uses .NET 4.0 (client profile) so you'll need to install this if you don't already have it. If you give Blogger2BlogML a try let me know how you get on.