Later today Microsoft will officially release Internet Explorer 9 Beta at a press event in San Francisco.
Several sites have written previews of Microsoft's latest browser, you can check out some of the new features at NeoWin and check out some performance benchmarks at Engadget. Additionally, there's also a very in-depth article over at ARS Technica.
In other news, Mozilla rolled out Firefox 4 Beta 6. This is a small update that fixes problems with stability on Windows and rendering errors with plugins on Mac OS X.