First off, thank you all for making the Twitter API the success it is.
 Our API is responsible for a staggering amount of daily traffic; many
times all of our web, IM, and SMS traffic put together.  That's great
news.

The bad news is that we have to take steps against those users that
are abusing the API to ensure its continued availability.  Starting
early next week we'll be deploying some simple API rate limiting.
Every authenticated user gets 1440 (one thousand four hundred and
forty) requests per 24 hour period, starting from their first request.

To put this in perspective, that's enough to make one authenticated
request to the Twitter API every minute, all day, every day.  Requests
to API methods that don't require authentication are not rate limited
because they're easily cached, and thus not a big load on our servers.

If, for some terrifying reason, you're concerned about needing more
than 1440 requests per day, you have two options:

1. Start using Jabber/XMPP to receive updates and direct messages.
We'll be writing up more information on this shortly, but a number of
developers are already using it for bots and other projects.

2. Email me privately and ask to be put on a white list.  Please
include the screen name of the user you're authenticating with and an
explanation of why you need to talk to the Twitter API more than once
per minute.

I'm happy to answer any questions you may have about our API rate
limiting.  We're just trying to make sure that our service is highly
available for legitimate uses and highly unavailable to abusers.
Thanks for your understanding.

--
Alex Payne
http://twitter.com/al3x