Multiple sources say the long-rumoured swoop by Twitter for TweetDeck is imminent.
They say Twitter filed papers on Monday to pay $40 million in cash and stock for its target.
Twitter is not commenting on the reports, and it's worth noting that previous rumours of a purchase by UberMedia in February didn't materialise.
TweetDeck is a neat bit of software that lets users organise their tweets better - by topic, users and so on. It's become indespensible for many serious Tweeters.
It's been suggested before that Twitter is ambivalent about clients like TweetDeck. They undoubtedly accelerate usage, but could be seen as cannibalistic.
Twitter previously acquired iPhone app Tweetie and photo service TwitPic to enhance its core service.