Twitter announced on Thursday that it can now withhold content from users country by country on demand, while still making that content available to the rest of the world. The news sparked widespread anger as critics accused the microblogging service of censorship and warned that the policy might impede popular anti-government movements such as those seen during the Arab Spring.

The FBI wants to keep its eye on social media users, according to a job post that invites software developers to submit applications capable of mining through sites such as Twitter and Facebook to identify possible threats. The post can be found on FedBizOpps.gov. The bureau has a detailed list of requirements for the app.

That invisibility cloak Harry Potter throws around himself to hide in plain sight soon may be fact, rather than fiction. Researchers at the University of Texas in Austin have demonstrated one -- sort of. The researchers hid an 18 cm cylindrical tube from microwaves by putting it in a shell of plasmonic metamaterial.

Vignette differentiates itself from other Android-based camera apps by adding cross-process, tilt-shift, double exposure and other sophisticated effects like infrared, as opposed to the general toy camera and retro effects commonly found. The paid version of Vignette adds full resolution to the mix.