follow / leave が API から出来るようになりました。
Twitter4J では未対応です。
やる気があれば今夜にでも。
・ API Documentation – Twitter Development Talk | Google Groups
follow
Enables notifications for updates from the specified user to the authenticating user. Returns the specified user when successful.
URL: http://twitter.com/notifications/follow/id.format
Formats: xml, json
Parameters:
id. Required. The ID or screen name of the user to follow. Ex: http://twitter.com/notifications/follow/12345.xml or http://twitter.com/notifications/follow/bob.json
leave
Disables notifications for updates from the specified user to the authenticating user. Returns the specified user when successful.
URL: http://twitter.com/notifications/leave/id.format
Formats: xml, json
Parameters:
id. Required. The ID or screen name of the user to leave. Ex: http://twitter.com/notifications/leave/12345.xml or http://twitter.com/notifications/leave/bob.json