Treemaps is currently under development, but here is a small taste of what you can expect in the future.

At the moment there is four algorithms implemented to get users up and running quickly. These are the SliceAndDice, Stripes, Squarified, and Strip algorithm. By extending the series object, the users can also add their own algorithms for layouting the data.
A levels object is introduced to let the users set wanted options to a specific level, this is displayed in some of the demos. The levels object is great for using a mix of several algorithms in the same chart.

Demos:
- http://jsfiddle.net/highcharts/sqxqq1ry/
- http://jsfiddle.net/highcharts/pa1eoqps/
- http://jsfiddle.net/highcharts/tm720ufm/