I think knowing why you want the follower counts would help us provide a better way to obtain the data.
For example, I look at profile metrics/authority when I'm setting a new profile up in a specific vertical. BUT, I know that I can use Topsy's twitter search to identify those authoritative tweeple. They have a nice hover-over feature that will show you follower stats for each user talking about the search query. I can also use TweetAdder to do this manually. I don't need to slow down, neigh, I would rather not slow down to record or even read a list of follower counts.
If you truly do want the data for bulk processing within a site, some sort of new tool.. then pulling it directly from Twitter may be the answer. It really depends.
