Step III

You have to take step III and also one or more years of post-graduate education to get a full medical license in most states in the US.

I thought it's 2 years in most states?

Is Step 3 an orthopaedic examination or a general physicians/surgical exam?

It's one year of post-graduate education in Wisconsin, but I'm sure each state is different.

Step three is general medical, so be ready to answer those pregnancy bleeding questions. I personally, didn't take it as I was grandfathered into the old FLEX exam, but I'm sure someone on the forum can tell you what it's like.

just finished taking Step III in Connecticut. All they require is an MD diploma, or an ECFMG certificate (my case) and prior passing of Step I and II.
It's not a bad exam, if you're just aiming to pass (though i'd hate to be any sort of an senior other than IM taking the exam)

grim are you also an IMG? I'm an aussie and am finding the process of gaining a US license very convoluted and confusing ...

Not confusing. Get into US residency. Finish. apply. Get license. It's easy.

I can't speak for myself, but this is what my cousin (Trained pediatrician from Russia, currently a radiology resident at Beth Israel in Boston) did:
1. Got the ECFMG certificate.
2. Took Step I, II CK, IICS. (Note: 1 may have followed 2 -- not important)
3. Took Step III in one of the states that has no postgraduate training requirement.
4. Applied for residency, having scored a 99 on all 3 exams, after spending some time as a radiology research persona at one of the hospitals in the Longwood area.