Mozilla released the second beta for its Firefox 3.1 Web browser to testers Monday. The latest release comes just seven weeks after the open source software maker launched the first beta of the version currently in the works. “So, even before the release of Firefox 3, we’d already been working on what will become the next release of Firefox and when we took stock a couple of months after the release, we realized that we’ve done a couple of really, really impressive and incredible things,” said Mike Beltzner, director of Firefox development.