i looked into the idea of Locum after residency, before i signed up for a fellowship...and there were some issues:
A. alot of hospitals want someone SENIOR coming into to the Locum work, not some fresh-out-of-residency person walking in with minimal experience
B. the companies that offer to arrange these Locum positions don't really have alot of experience with Pathology, as they are generally companies that deal more with other 'hotter' Locum fields (Radiology, Neurology, ER, etc...)
C. I couldn't find a single person to speak to who had left residency and gone into Pathology locum work successfully, despite all the grand promises of these Locum companies, i needed some evidence that it could even be done..
and as other said, state-state licensing would definitely be an issue to think about...