I believe that this highlights a cardinal rule that all interested in HPSP should remember. NEVER take the word of a recruiter as gospel. Remember these simple rules:
1. If a recruiter tells you, don't believe it.
2. Never believe what one person tells you. EVERYTHING should be corroborated.
3. The military has a bad habit of changing things quickly and updating information slowly. It seems things change but brochures, web sites, and recruiter training doesn't.
4. Never do it for the money.
5. The only rule is that there are exceptions to the rule.
I am a former Army HPSPer in a FYGME program at an Army medical center. I am pretty comfortable with how the process works. As the previous poster mentioned, there is really no big difference between the way the military does things and the civilian world does. The same ACGME accredits civilian and military training programs. Early in your 4th year of medical school you will begin the process of applying for FYGME. That's just a fancy military way of saying exactly what it stands for, "First Year Graduate Medical Education". I don't have the time to get into the entire process, but suffice is to say that when it's all done you will have several options DEPENDING ON YOUR CAREER CHOICE. Some residencies will allow you to sign contracts before you graduate medical school that enable you to complete your entire training with the military. I do not recall which specialities allow this, but mine, pathology, does. I have signed a 4-year contract. Don't quote me, but I think Ob-gyn also did this. For the remaining specialities (or if you decide to opt out of the "complete" contract) you sign a one-year contract to do at least one year of post-graduate training with the military. Unless you are deferred to a civilian residency (and this is a whole nuther story) you must do at least one year of training with the military. The practical reason is that after you take Step 3 of USMLE (or Part 3 of COMLEX for the DOs) you apply for your unrestricted state medical license. This is usually done during or after your first year of graduate training. You are then a "doctor", able to prescribe, write orders, etc. with abandon (not just in a controlled hospital setting). The military needs at least this out of you.
From here the road diverges to many different points. I think that the most salient is to mention that if you take the one-year contract with the intention of completing your residency training with the Army you will apply for the residency during your first year of graduate training (aka the "intern" year). Sometimes there are less residency spots than there are interns queued up to take them. If you are the unlucky one who doesn't get in, you may be moving. For the most part (and almost uniformly with the primary care (family medicine, internal medicine, pediatrics) you will easily pass on to the rest of your residency from the intern year.
There's so much to say but the hour is late (for us path-types), I hope this helps,
G