Sunlight intensity based global position system – It turns out you can geo-locate underwater sensors to within a few kilometers just by measuring the sunset and sunrise times. It’s a beautifully cheap way to figure out where fixed-position outdoor sensors are, since taking light measurements a few hundred times across a day is simple to implement, and doesn’t take much power or computation.
NSNotificationCenter with blocks considered harmful – Managing the lifetime of memory allocations is incredibly hard, and this is a cautionary tale in how nasty it can get.
Blackhash – Do you really trust your security audit company with your hashed password files? An interesting approach that allows them to do some limited testing, without handing over the data itself.
Geo-located Twitter as the proxy for global migration patterns – Understanding how the world is connected by analyzing people who tweet from multiple countries.
Analyzing the Iranian Embassy bombing in Beirut from photos – The format of the slideshow is a bit hard to navigate, but it’s worth stepping through. Felim explains how he used a combination of ground and satellite photos to verify that a suspect video was actually taken at the right time and place.