It tends to be a very small world where you get to know everyone after a certain point, or you know someone who knows someone, and jobs tend to be had by word of mouth. If you have a good reputation (which can be gained working on problems on visible open source projects), work tends to present itself. Even more so than in other fields because it is such a small world, despite the enormous amounts of money involved in semiconductors.

There aren't a lot of advertised jobs, but I think this is often because they tend to get filled via word-of-mouth and employability is rarely a problem for a decent embedded engineer.