
Microsoft's new RC is ready-to-ship code, and there are only a few bugs expected to be left.
From the betas, the RC offers improved JavaScript and includes all the 2,000 changes made since the first beta.
As of the RC, Microsoft claims their IE9 JavaScript engine is the fastest of all current browsers (based on SunSpider benchmarks).
Security is also a big factor in the browser, with an improved ActiveX filter and SmartScreen malware protection in the download manager.
RC for those interested: http://windows.microsoft.com/ie9