I was once asked to be in charge of an acquisition. We would let the new group (over 100 people in a building on the East Coast) keep doing the same work with the same management. What they didn't know was that that is code for keeping them isolated from the real company. And we would even assign a multi-talented team to integrate their product with our doc group and engineering groups - in a show of how important their work was to our company. What they didn't know was that that was really done so that I could prepare a list of technology worth saving for the CEO (Let's call him Larry). The plan was to spend perhaps six months understanding their code, another six months taking the parts we want, and then letting them go. There was really nothing they could do about it. We simply wanted to consolidate our position in the market.
Since then I've spoken to other CEOs who were acquired by that company. They boast about how they were allowed to keep working on their projects and how they were important to the company and their great relationship to Larry as part of a Fortune 50 company. But then, over time, they found they weren't being given freedom anymore and they left. They just never really understood what was really happening.