We just launched a Movable Type plugin for MailChimp.
It lets you add a subscriber box to you or your client’s Movable Type blog/website that passes subscription info over to your MailChimp account. You can download it from our MailChimp Plugins page.
TypePad is next.
Want to build your own plugin for MailChimp, or hook our email marketing engine into your program? You can link us into just about anything, like your CMS, CRM, or e-commerce cart (whether you program in PHP, Ruby, or .Net). Just use the ever-expanding MailChimp API. We’ve got a dedicated API team that is constantly improving and documenting everything. View API Documentation.