Currently it uses html <div> and <span> you can only drag the things around. There's also some anamolies with displacements of the arcs less than 2 x the size of the images used to build the paths.
When the DSN happens, it should appear here.
It uses Walter Zorn's wz_dragdrop scripts for the drag and drop, and builds the paths in dynamic HTML layers. A servlet provides the stock arrows, lines, bends and shapes as I got bored trying to photoshop 200 different arrow heads.
[eta: dns for lapisblue is now up; pages work with firefox or safari on OS X but are untested on other platforms, and crash IE on OS X]