I know it's too late to publish this post, by this time most of you guys must be already aware of this.
But anyways for those who are not much aware of the updates you can refer to this.
Beta release of Silverlight 5 is expected for spring 2011, and the final release for the end of 2011.
I won't re-post the list of planned features here. You can get all the details on Scott Guthrie's blog.