The English and Chinese sites for the news service have been inaccessible since late Thursday, but the reason isn't clear.
Following a similar change to its mobile app, Twitter has moved and renamed the familiar compose-tweet status box on its website.
Chinese state-run media outlets are calling on the government to punish "pawns" of the NSA's Prism surveillance program.
American tech firms are caught in the cross-fire between China and the US over cyberespionage. International politics specialist Shen Yi says this storm isn't likely to blow over soon.
Images that purport to be the rumoured small iPad have popped up online, and there's no rear camera.
The microblog is apparently testing a mobile feature that would map tweets posted by Twitter users, whether you follow those users or not. Privacy advocates take note: it seems to be opt in.
With ever-increasing restrictions on online activity, Chinese authorities are trying to make Internet service providers act as Web police for the government.
Twitter acquires the simple blog platform, a rival to Tumblr, but discloses no terms of the deal.
Twitter envisions itself displacing the canonical water cooler for TV discussion; now it just needs to make some deals.
Twitter CEO Dick Costolo says mobile usage and revenue are outpacing the desktop Web version of the microblog, and that he doesn't concern himself about an IPO.