Wouldn't it have been more
cost effective just to publish up coupons and discounts on an rss feed and web page?
The claim it is twitter that is doing is not right, it is the offers, and making some of those offers twitter only deals further skews this.
I have no feelings either way for twitter, but Dell brand is huge, and people will follow what Dell do, so whatever odd thing they get up to if someone can get some cash off by following it will show a 'result'.