This is common for consulting companies with MBA or field-related masters studies as well. The company effectively loans you the tuition money and forgives the loan if you come back for at least 2 years post-graduation. If you leave early you have to repay the loan with your own money.

I'm not sure this could work with normal raise-type compensation in the software world due to the difficulty of enforcing such a thing or clawing back money from people who leave early. The traditional way this was done was with pensions that ramp up with length of time at the company, but those are few and far between these days due to the overhead hit on financials.