There used to be a thread on this, title was something like "DO vs. MD", last modified ~October, but it's disappeared -- possibly deleted by the thread starter (a DO enthusiast), since there was evidence showing that DOs are at a real disadvantage compared to MDs at most countries outside the US.
To summarize the findings, the official osteopath site lists a bunch of countries where DOs "have in the past been licensed"...pretty lame wording, since as it turns out, various govts' and doctor recruiting sites explain that DOs are handled on a case-by-case basis for most countries outside the US (and those Canadian provinces that accept them out of hand). In other words, if you want to practice overseas, you generally have to go through a whole bunch of red tape to ensure you can practice, assuming you're not a priori rejected, and if you want to do locum tenems, you're screwed. If these are your interests, you're better off with an MD, even if as an IMG.
-pitman