Taskwarrior also supports task dependencies. It has a lot of similarities with Hiveminder, in that you have to specify dependencies as task IDs, though it's a little more flexible and less opaque than Hiveminder is. But there's still no gesture support, and that's because Taskwarrior is a command line tool.

I think of myself as being a command line junkie (I'm far more likely to do math by bringing up a shell and running "bc -l" than any other calculator), but I think this is taking it a little too far even for me.

It seems like Taskwarrior has a lot of features and is really solid. It even supports synchronization through a few methods, and it's open (in both the source and API senses) enough that people have gotten a variety of layers working over it, including a web interface. (Which, sadly, I haven't had the time to get working.)

I really like the concept here and I totally support these guys, but, for now, Taskwarrior creates too much overhead for it to be a successful tool for me.