Microsoft just sent out invitations to an event in San Francisco on February 10:
IE in San Francisco (2/10)
Members from the Internet Explorer team (and some special guests) will be visiting San Francisco in two weeks to share some important news. I know it's an extremely busy news week already, but we're hoping you can join us.
No further details, but it's logical to assume that this will mark the public release of the Internet Explorer 9 Release Candidate. I'll be there and will have a full report.
The public beta of IE9 was released on September 15 (see my full review and screenshot gallery). Since then, Microsoft has been actively soliciting feedback and has released two additional developer previews. I expect to see a handful of significant UI tweaks and greatly improved performance. This RC should be nearly final, and I expect a final release within 60 days, probably in time for the MIX conference in mid-April.