It seems that the latest version of Flock works fine with Mango!
For some reason, categories are not properly sent. Since this is also a problem with Google Docs, I need to investigate what the issue is.
Update: It seems that as of version 0.2.4 the categories issue has been solved for Flock
Blogged with Flock
He has used Mango to publish the website for the Flex Camp Boston he is currently organizing. He applied a nice custom skin and is using Mango to publish news in the home page and to maintain the website content using "Static Pages". It is a very positive review and I hope to get more participation like this from the CF community.
Thank you Brian!