It turns out you can fairly trivially embed dashboards.
This just takes some code from example 1 and repeats it to get a 4 column layout. The repetition is convenience only. If I put more effort into it all 4 columns would be different, but I'm just lazy enough to not do that.
It's actually 2 dashboards (it should be 3) -- a dashboard, and the left uses dashboard_get_node() and the right uses dashboard_get_node. They can get different nodes.
Doing an odd number of columns might require some good CSS foo to make them space evenly, but I think it should be doable.