This is very similar to the questions that are permanently coming up in Business Intelligence projects when OLAP is required. If I am looking at the way how I played with your prototype I have following suggestions:
-that there are use cases where I would prefer to see/treat the group of tags more as a bread crumb trail – means that the sequence how the tags have been selected is relevant and the UI should allow to things like “drill up” (today only reset or the more difficult to understand concept of “select a tag that is in the group of selected tags again but don’t do it in the UI in the group of the selected tags itself but in the table”
-there is a value of providing “standard hierarchies for navigation” (or easy access to those prefedined groups of tags) even when there is the full nav-flexibility as your MD UI prototype is motivating.

I hope this makes sense, please feel free to ask if anything is not clear why I am connecting this to the OLAP UI experience.

Best regards,
Ralf

I did a version Ajax-style, and the JS overhead was worse than the server delay. But it’s probably no different than Flash or Silverlight, in that for immediate responsiveness you’d want to cache as much metadata as possible locally.

But that’s entirely separate from the question of whether it is conceptually intuitive to do things this way, or if it isn’t, how it can become so.

You’re right that Freebase is worth taking another look at.

That’s a good idea! I like the notion of showing more, but in a controlled way, rather than showing less.

This reminds me a little of the search interface in Freebase, but that seems to be a little more self-explanatory.

So if you select the “silverlight” tag, it would be strongly selected it in the cloud, and you would only see entries for silverlight in the search return list. But you would also see a weak selection of “flash” and “stories” in the tag cloud. If you then select “flash” in the tag cloud it would strongly select “silverlight” and “flash” and weakly select stories and any additional tags associated with “flash”. The list would then show entries with both flash and silverlight at the top, followed by stories only about silverlight or only about flash.

As you continue to select more tags you get more search results and more associations. The list being sorted by the number of matching tags.