I spoke to a travel agent friend of mine, specializing in corp travel.

He says they get transferable status, upgrades, and miles they are free to distribute as they see fit.

T&Cs say they (the agency, not the recipient) aren't supposed to sell or barter these incentives, but the threat primarily hangs over the agency if the airline discovers this and enforces the policy. The incentives are often used to sweeten deals, sometimes unrelated to that particular airline, which technically is selling them. Basically, the retail value of the incentive can be charged back to the agency, though he's never heard of that happening in decades of being in the business.