Human Connectome Project
humanconnectomeproject.org
humanconnectomeproject.org
Circuit neuroscience in Drosophila or the mammalian retina suggests neurones and synapses are indeed the level of detail we'll need in order to gain insight into computational mechanisms. So we're a long, long way off -- don't be too impressed by this particular dataset (which is insanely coarse!).
The WU-Minn side of the project is seemingly more active, and their dataset is much, much easier to obtain: http://humanconnectome.org/data/. Their scripts for processing the data are up on github at https://github.com/Washington-University/Pipelines.
Edit: oh here's one http://io9.com/see-the-first-ultra-high-resolution-3d-scan-o...
If I'm reading it correctly, it looks like either 1.5mm, 2mm, or 2.5mm, depending on the dataset.