Today I did some work on the Grid Data Format aka gdf, described here: http://yt-project.org/gdf.txt
I've been attempting to use this to convert an Athena dataset to gdf, then read that into yt. As of right now, I am testing on a single uniform grid, and am able to load it, find the max of the fields, and do a few other things. However, I can't seem to get slices/projections to work. Anyways, I'm not sure how much time I'll have in the immediate short term to work on this, so if anyone wants to jump in that'd be awesome.
I've pushed what I have to my fork of yt: https://firstname.lastname@example.org/samskillman/yt
Here is the test dataset: http://corvette.colorado.edu/~skillman/dload/gdf0001.h5
You should be able to do: yt load gdf0001.h5
As a warning, I haven't tested a bunch of stuff, so there may be stupid mistakes lurking around. Feel free to email me or respond to this list if you have questions.