Yeah, the pass rate is in the low 90% range. I have to say, though, that I didn't feel like the ABIM exam had much to do with being a good internist...not that folks shouldn't be able to pass it...but to me it consisted mainly of regurgitating a lot of factoids, and wasn't a problem solving test like the USMLE Step 2 and 3, which require that you actually have a clue about management of common clinical scenarios. The ABIM exam seemed more about memorize-and-regurgitate factoids, many of which could be looked up in a book anyway (like obscure rheumatology tests, etc.). Day to day internal medicine practice is more about being conscientious about following up on test results, managing diabetes and hypertension, and doing relevant health screenings, such as cancer screenings, for your patient. Not that it's not important to know something about rare diseases, but I felt like this exam just tested rote memorization, not thinking or problem solving.
I do think it's somewhat of a scam in the sense that selling the review books and giving the exam is a big money maker. The test costs >>$1000 (even for residents, who make say 40k/year and are paying back hefty student loans of several hundred dollars/month or more) and the review books cost $500 or so minimum.