I recently experimented with using photogrammetry to do mapping for OSM and thought I would post the results on here.
I started by taking quite a few photos of St Dionysius church in the centre of Market Harborough using a cheap digital camera (Pentax Optio S5i).
Once I got home I spent some time experimenting with various pieces of software before settling on Bundler, http://phototour.cs.washington.edu/bundler/. It took a bit of messing, isn't exactly user friendly and the whole process can be slow, but produces some pretty good results.
The software outputs .ply files which can be opened with Blender to get an idea of how successful the bundle adjustment was. This video shows the point cloud that was created using my photos. http://www.youtube.com/watch?v=cApFzm4KHiU
I cheated a little to get the data into a usable format for JOSM by taking a screen dump of Blender and using PicLayer to give me a guide. I then traced the building shape and positioned using a GPS trace from a previous visit.
When time permits I hope to take this a little further and get a high detail map of the surrounding buildings of Market Harborough town centre done.