Standard CSS3 rotate should work in IE9, but I believe you need to give it a vendor prefix, like so:
-ms-transform: rotate(10deg);
It is possible that it may not work in the beta version; if not, try downloading the current preview version (preview 7), which is a later revision that the beta. I don't have the beta version to test against, so I can't confirm whether it was in that version or not. The final release version is definitely slated to support it.
I can also confirm that the IE-specific filter
property has been dropped in IE9.
[Edit]
People have asked for some further documentation. As they say, this is quite limited, but I did find this page: http://css3please.com/ which is useful for testing various CSS3 features in all browsers.
But testing the rotate feature on this page in IE9 preview caused it to crash fairly spectacularly.
However I have done some independant tests using -ms-transform:rotate()
in IE9 in my own test pages, and it is working fine. So my conclusion is that the feature is implemented, but has got some bugs, possibly related to setting it dynamically.
Another useful reference point for which features are implemented in which browsers is www.canIuse.com -- see http://caniuse.com/#search=rotation
[EDIT]
Reviving this old answer because I recently found out about a hack called CSS Sandpaper which is relevant to the question and may make things easier.
The hack implements support for the standard CSS transform
for for old versions of IE. So now you can add the following to your CSS:
-sand-transform: rotate(10deg);
...and have it work in IE 6/7/8, without having to use the filter
syntax. (of course it still uses the filter syntax behind the scenes, but this makes it a lot easier to manage because it's using similar syntax to other browsers)