In this post, I am going to list down the key new features introduced in BizTalk Server 2013 Beta and also provide some useful links that describe how to use those features. But, to start with, this is where you can download the Beta bits for BizTalk Server 2013 from - http://www.microsoft.com/en-us/download/details.aspx?id=35553.
Now the list of new features.
For a complete list of software stack supported, see Hardware and Software Requirements.