I am hearing more and more of hospitals hiring NP/PA to help with workload on specific services, such as sugery. They are doing this largely because the residency review committees are starting to crack down on the hours resident put in. However, the patiens still need to be taken care of. Some hospitals are filling the gaps by having NP/PA do some of the work. It's not huge yet, but may be a trend worth watching.
Bascially, however, any physican can hire a NP if s/he is willing to comply with whatever that state's supervision laws are.