Yesterday, Yahoo! announced that they are releasing a new API to the public. According to Wired Magazine's newly rejuvenated (yay!) Webmonkey blog:

The Yahoo Address Book API offers JSON/XML data responses and can be used for common tasks like syncing with another address book, e-mail address auto-completion, obtaining unique identifiers and more.

This is exciting news for the nonprofit sector since we rely so heavily on "Tell a friend" marketing for list growth. While most nonprofits will have a hard time using the API on their own, I have to think that the software vendors are already dreaming up new tools for us to use.