Up until the 70's people would stay in a job for 20 - 30 years and would not change jobs too much, In the 80's - 90's people started to change jobs every 5 - 9 years. With the current worker, they change jobs mostly in less than 5 years and are very mobile and will often change countries as well as jobs.
It is a growing trend where workers are more mobile than they used to be and don't mind having a go at other skills.. Not uncommon to see an Engineer working on a building site as a chippie, for instance.

There is also another form of mobile worker, and it is the worker who now works out of a van, like a mobile mechanic, or a mobile PC tech who comes to your home, and even mobile Hairdressing... huge in the 90's but this has been a decreasing trend in the 00"s. They seem to increase after an economy collapse..

Definition from:
http://wfnetwork.bc.edu/glossary_entry.php?term=Mobile Worke...

Workers who, “perform their work in multiple locations such as customer sites, company offices, their homes, vendor offices, planes, and hotels” (Richman, Noble, & Johnson, 2002, p. 9).