Hierarchical Categories

Hi,
I have a feature request.

I have begun using categories, which are great, but as I increase the number of categories I want to use, this will become unwieldy. What I'd love to see is support for hierarchical categories. Like for example:
   Technology
      Architecture
      Languages
         Python
         CLIPS
      Hardware
         etc.

Then if you click on Technology you'd see all the posts in cronological order from all the child categories. There are of course also other good reasons to have this. 

I feel like the basic infrastructure might already be there, since dates sort of work this way now, with a hierarchy that looks like yyyy / mm / dd.

Are there any plans to do anything like this?

Thanks,
Rand