Twitter is growing like crazy — in fact, it’s still one of the fastest growing sites on the web, despite being around for a few years. Now Twitter CEO Evan Williams has announced that they’ve surpassed 145 million users mark, and they’ve adding almost 300,000 users every day, which means they’ll be surpassing the 150 million mark very soon. He also mentioned that, quite surprisingly, 16% of new users are signing up via mobile devices.

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Twitter’s new “you both follow” feature has been in testing for a few weeks, and now it’s live and on every account. Basically, it shows the users you and the Twitter profile you’re visiting are both following.

We dunno how useful this really is, as you’re already following those folks.

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Twitter has officially launched its new Tweet button, which pretty much replaces the TweetMeme button which has been used across lots of sites.

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Twitter is endlessly expanding and is hiring new folks. To make the hiring pitch easier, they’ve created a fun video showing the different sides of Twitter.

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According to a new rumors in the Twitter-verse, Twitter will begin allowing users to take part in the “sponsored Tweets” platform, by paying to get featured and get more exposure and followers. Twitter hasn’t confirmed anything, but seems like an obvious idea and another way for Twitter to get some revenue.

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Yesterday, during the pivotal game 7 of the NBA Finals between the Lakers and the Celtics (Lakers won, FYI), Twitter users were posting over 3,000 Tweets per second — a new record. This is far more than the average of around 700 tweets per second, and more than even during large World Cup matches.

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Twitter has finally launched its ads, for the time being, in trending topics. The first company to buy an ad-space was Disney, with ads for the upcoming Toy Story 3. It simply appears as a regular link at the bottom, with an indication that they’re “promoted”.

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Twitter has acquired analytics company Smallthought Systems, which makes Dabble DB and Trendly, apps for displaying and collecting analytics. Twitter is expected to integrate the new software so better track tweets — and especially, paid tweets.

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