I had the same thought. The way bitcoin works today this isn't possible, however a new generation of virtual currency might be able to do something like this. Basically, coins would be allocated to contracts for certain types of calculations. Those calculations would be paid for by xyz company. The calculations would be broken up into pieces and distributed to workers to calculate and shares would be given based on the amount of work done.

The problem I see with this is that instead of the currency now being self-sufficient, it is now reliant on new contracts to generate new coins and the coins are now backed by an actual currency (because xyz company paid for them). Also, generating new coins wouldn't validate the previous ones.