Blog compatibility
TypePad
The recommended way of posting your tweets on your TypePad blog if you have
a PRO account is to invite LoudTwitter as a guest author.
Otherwise LoudTwitter can use your credentials to post using the Atom API,
or using the secret moblog address of your TypePad account.
Vox
Vox can generate a specific secret email for LoudTwitter exclusive usage. Vox also gives you the ability to configure this email to automatically tag the post or apply custom privacy settings.
You can also login using your Vox blog address in the openid login field.
Movable Type
Movable Type is very flexible, it should work using any posting method
LiveJournal
LiveJournal has been tested with Atom credentials. But if it doesn't work, we suggest using the post by email feature of your account.
Here are good instructions on how to setup LT with LJ, including advanced features like tagging, using email posting
You can also login using your LJ blog address in the openid login field.
Wordpress.com
Trusting WP faq1 and faq2, There is no ATOM implementation in WP. Luckily a XML-RPC interface has recently been added to LoudTwitter.
Self Hosted Wordpress
Thought it hasn't been tested it should work using ATOM API, since it appears that wordpress supports it
Blogger (aka blogspot, aka google)
It should work with email posting (you can create a special address just for twitter). Atom posting is not supported.
tumblr
Email posting has been successfuly tested with tumblr.
...more
let us know!