RC is an abbreviation for Release Candidate. WordPress 3.3 RC (Release Candidate) 1 was actually released last month on November, and the release date of the new WP 3.3 is planned to be on December 13, exactly a few weeks before Christmas if everything runs well.
Again, many changes are included inside the RC version, including welcome panel, which will show straight after you installed a wordpress blog, and also admin pointer which now has a nice blue sky color(previously with dark color, see my older admin pointer post) , complete with dismiss button in case you don’t want to see it.
Extra New Icons seen on WordPress 3.3 RC 1
By setting up a blog offline using the RC version (this is a download link) a few days ago, I notice a huge difference with the admin bar. And that’s the new extra icons above in admin bar, which are “updates” icon, “Comments” and “Add” icons.
Those tabs are currently only labeled with texts, and it seems that there will be icons replacing the texts, which I personally find very cool.
Here is the screenshots of the old tabs in admin bar:
And here is the new icons on the top (yellow highlighted):