It looks like UberTwitter has decided to turn off advertisements in their popular application until they have a chance to release a paid variant. Users were quite inflamed about the new and intrusive ads though they have slowly been creeping into other free apps.
UberTwitter has posted the following announcement on their website:
Ads Have Been Turned Off
We have been listening and have heard you loud and clear! We will not turn advertisements on again until we can offer a a paid option with no advertisements. The paid version will be less then $5 and will likely be a year long subscription model, i.e. all upgrades for a year. If you purchase during the beta period, the year won’t start until we release version 1.0. Thank you for your patience and your feedback! –@CodeWarden
Looks like you just need to close UberTwitter and restart it for the ads to go away. It might have been better if UberTwitter had notified users before and asked for their opinion on how to monetize the app…