Some leaders in the testing industry continue to maintain that test teams are "gatekeepers," the watchguards for quality. This makes me sad. I've spent many years now in development organizations where everyone-programmers, architects, DBAs, system administrators, analysts, customers as well as testers-takes responsibility for quality. These teams have delivered software whose quality is many levels of magnitude beyond teams where the testers were the quality gatekeepers.
One argument I hear from people who advocate separate, "independent" test teams is that testers who work together with developers (especially those who report to the same manager as the programmers) are vulnerable to a programmer suggesting that their "minor" change ("It was just one line of code") doesn't warrant any testing. This implies that the programmers don't care if they introduce defects into the software.
Crummy programmers influencing gullible testers isn't an issue to be solved by separating them into different, siloed teams. What we need to do is: 1) hire people who care about doing a good job, and 2) give them the time and training they need to do a good job. It's not an organizational issue, it's a management issue.
All the good testers I know are independent thinkers. If a programmer tells them, "I only changed one line of code, you don't need to test anything," they'll analyze the situation and decide for themselves what testing is warranted. If there's a time crunch, they'll provide the customer with information about the risk of not doing all the testing they think is needed, and let the customer make the decision.
My independent streak doesn't change when I report to the development manager instead of to the QA manager. There was a time when I was proud to be the "Quality Boss" and hold the keys to production. Back when I did that, the quality of the software we released was average at best, and our product wasn't competitive. Seeing the results of the "whole team" approach to quality has convinced me that more collaboration and communication, not less, is the way to go.
Don't worry about whether your test team is separate or not. If you're a tester, get up now and go start talking to the programmers. See how you can help them. See how they can help you. If you're a manager, start hiring the best people you possibly can, and start training the people you have to care about quality and learn how to deliver high-quality software.