Now, if you are not a programmer, you may not have any idea what OAuth is. Back in the early days of twitter, one would use your username and password to allow you to access Twitter. Same thing on the iphone. You would be asked to enter your twitter name and password and the phone would remember this and all was good with the world.
Because this is not a very secure way of doing things and leads to various security and anti spam issues. The fix? Switch to a more secure process using OAuth. Great right? Well not really. For the programmer, this add another layer of complexity to the program. For a long time this did not matter since twitter supported both. Well those days are over. Tomorrow Twitter will be OAuth only! That means if your favorite twitter app or application that makes any calls to Twitter, will stop working if they did not update the code to support OAuth or XAuth.
here is a link to the countdown on twitters page. http://countdowntooauth.com/
So you have been warned. If your favorite twitter app (or app that does things with Twitter) suddenly stops working tomorrow, you may have to just look for another app because if they have not fixed it by now, its not likely its going to be fixed.
BTW; if you are a bit geeky, you have a quick look at an older post here. http://www.perivision.net/wordpress/?p=3075
or if you are REALLY geeky, check of the page on OAuth. http://oauth.net/