LinkedIn, the social network mostly inhabited by technology professionals, now offers a great feature that allows you to explore various features of the linked in crowd such as company affiliations, age, and years at a company.

This led Louis Gray to create this excellent graph:

Most interesting to me was the very low tenure time at Google, though this may reflect a large number of new hires rather than people leaving the company. However even established titans like Microsoft and Apple appear to have something of a revolving door where people are jumping and climbing aboard other big ships at a surprising pace.