The JDK 7 project has reached the Developer Preview milestone. If you've been waiting for JDK 7 and want to take it out for a spin - this is the release for you. There are links to a feedback forum and a way to submit bug reports on the java.net download page. The JDK 7 team's plan is to try to evaluate and act on the feedback until the end of March, so if you spot something, it's best to mention it sooner rather than later.
The final release of JDK 7 is expected towards the end of July 2011.