Most hospitalists are board certified IM docs and a few may have subspecialty connections (usually Pulm/CCM). There are a few hospitalist fellowships out there but it is really a seller's market right now because of the push by many hospitals and medical groups to hire them that 3 years of IM w/ board certification is enough. Use of hospitalists is documented in trials/studies to reduce cost of inpatient care and length of stay. IM residency training essentially prepares you to be a hospitalist, more than it does to prepare you for outpatient medicine. My experiences with hospitalists has been fairly varied and rich. At our primary academic center, they serve the more traditional role of an attending physician who in essence serves as an admissions gatekeeper and guides resident/intern decision-making. At the private hospital, its a bit different as the hospitalists have less of a role in teaching and tend to dump work on the interns/resident because they too have a large number of patients. Being a hospitalist is a lot like being an eternal intern....except your efficiency and knowledge are much improved. You admit all the patients and are responsible for all the details. The social issues are the same, the referral/consult hassles are about the same (a bit lighter in private practice with some consultants hungry for more work and cash). The pay right now is fair...better than for a traditional internist...probably landing about $150K a year or so. Call is part of the equation as most hospitals of size need an internist on call 24/7. As for additional training, CCM is probably the most important as the acuity of illness demands special attentions...but some medicine programs excel in delivering this type of training.
Its not a bad gig...but you have to remember a couple of things. 1)Gen med patients can be extremely tedious 2)You can't reinvent the wheel with your admissions 3) Medicine can't refuse an admission and you are at the ED's whim(unlike surgery, psych, and every surgical subspecialty) 4) Dispo issues! 5) You still are a Jack-of-all-trades, schooled in all, but master of none. 6) lack of patient "ownership" (disad for some)