Ploticus has some support for timelines. I've just recently started using it in my CT displaying data over time.
A quick search of the Ploticus web site turns up these example scripts at these 2 urls:
http://ploticus.sourceforge.net/gallery/gall.hbars.html ,
http://ploticus.sourceforge.net/doc/clickmap.htmlI'm still getting familar with what Ploticus can do, as it has so much capability. In fact, the page you linked to seems likely to be using ploticus itself--- with its own standard scripts to feed in the exact format to Ploticus so it is easy to use and have standard formats.