How to get a list of *new* followers using the twitter API

Question

I need to periodically return a list of all new followers of a twitter account (i.e. since the last time the list of followers was retrieved), but the Twitter API only seems to provide functionality for getting a list of all current followers of the account.

Apart from getting this full list every time and comparing it against a stored version of the last time it was retrieved, is there any other way to get hold of the new followers?

Sites such as divvoted.com, mrtweet etc must do this somehow! Am I missing something or does it just need the round-the-houses approach described above?

Answer 1

Yes, you have to keep the list of followers since last update, because twitter does not associate api clients to state. The definition of 'last time the list was retrieved' lacks 'by whom'.