In an interview with Reuters, Mozilla Vice President of Engineering Mike Schroepfer has at last revealed Mozilla's expected time frame for the launch of the final Firefox 3.0 release: late June. A fourth beta version of the browser came out earlier this month, and we know a beta 5 release is expected in a week or two. Schroepfer says the fifth beta will include tune-ups to the browser's look and feel as well as further stability improvements. After that, Firefox 3 will most likely hit the release candidate stage, at which point Mozilla will continue to iron out bugs until it deems the browser ready for a mainstream launch.  Mozilla's website currently warns that Firefox 3 betas are intended for developers and testers only, but Mozilla reportedly plans to revise the site and remove that warning.