for Lotus Notes users I have developed a GTD template. It is integrated with your Mail template, uses Projects and Actions close to the GTD sense. Existing PDA and smartphone synchronization are still working with it!
It is still beta. You can check it here (documentation included):
(the first few entries are about GTD, others are Hungarian - sorry for it)
Please feel free to write your comments and opinions about it either here or on the blog.