Indeed. My company even does this semi-formally, with an 'alumni' network, events, and stuff like that. This works out insanely well in our field (management consulting), as the philosophy of the company is that our consultants will eventually leave and we want those people (who we thought were great enough to hire) to hire us as clients at their new firm. It's done fantastically well, and fostering a culture of (not exactly) assumed transition and migration does wonders. It's not looked down upon at all to take a full time job with a consulting client, for example.