These aren’t necessarily appharbor specific, but i figured them out while trying to get my blog up and running on appharbor:
1. The default BlogEngine.Net source isn’t set up as a web application project, you’ll need to download the web application version of the project to get it to build in appharbor
2. Because the default BlogEngine project is not a web app, most themes aren’t set up for the web application solution, so you’ll need to change the “codefile” reference in the site.master file to “codebehind” for site.master.cs or else you get an error like “site.master.cs does not exist”
3. I also had to move the content files from outside of the content folder to the top level folder of the theme. It looks like that’s the expected location for BlogEngine.Net, but most themes I downloaded have the needed files in a content folder.
And if you’re just getting started, this blog post was helpful: http://ypblog.apphb.com/post/Hosting-BlogEngine-blog-on-AppHarbor.aspx
you can just substitute bitbucket for git and it should work just as well, if like me you prefer bitbucket for your source.