This morning an app of ours was rate limited when sending direct messages. Here is the response we get from the API: {"request":"/direct_messages/new.json","error":"There was an error sending your message: We know you have a lot to say, but you can only send so many direct messages per day. (<a href="http:// help.twitter.com/forums/10711/entries/15364">click here</a> for more info.)"}
Following the link: http://help.twitter.com/forums/10711/entries/15364 it says that being whitelisted should lift the limits. Our IP address is 209.123.162.18. I don't have the original email since I submitted it via the online form. But I did exchange emails with @dougw and know that sent 100+ requests in under an hour earlier this week.