Dropbox just bought online collaboration and communication tool Cove, for an undisclosed amount, according to Forbes. Also acquired in the deal were the engineering team that manages Cove, former Facebook executives Aditya Agarwal and TechFellow winner Ruchi Sanghvi, who will join Dropbox immediately. Akhil Wable and Joshua Jenkins will also move over to Dropbox, both being former engineers at Facebook as well.

“Building a world-class engineering organization is a top priority for us,” says Drew Houston, Dropbox co-founder and CEO. “The team at Cove represents some of the best talent in the Valley and we look forward to the technology, skills and perspective they will bring to Dropbox.” This is the first acquisition for Dropbox, which is estimated to be worth $4 billion, but the buy was mostly for the talent coming with Cove, as it has been said that Agarwal will become Dropbox CTO.

Dropbox didn’t explain too much about what the team from Cove would be working on, but Aditya vaguely stated that the “product vision for Cove and Dropbox is very much aligned and the infrastructure we’ve built at Cove can be utilized at Dropbox.” The San Francisco-based Dropbox has over 45 million users, and logs 1 billion files every three days. Microsoft might hope to compete with Dropbox at the launch of it’s revamped version of Skydrive which is said to coincide with the release of Windows 8.