We're primarily focused on the US & Canada right now, though we do have customers elsewhere.
One distinction to make is that we're not like the "incumbents" you mention. We're more like property management software (or "property marketing" might be closer). We're not trying to build a destination site and attract renters to it. Our goal is to make it easier for an owner to market across these types of places.
Tactically speaking, we go out and vertically integrate anywhere meaningful to vacation rental marketing, and allow an owner to upload their home info once and then simply click to opt into whatever channels they want. They get to manage it all in one place and everything stays in sync (no more juggling multiple calendars, rate tables, etc).
So, think of us like the DSP's that emerged to help advertisers deal with all the various ad networks that popped up. It's a pain in the ass to go integrate with all of them. For now, we're launching with the major listing sites (similar to the incumbents you mention) in the US. We also provide the other several other helpful marketing tools - their own website, their own Facebook Page (a great 'CRM' tool, if you will), auto-responders, Craigslist ad poster, etc...
I think that's quite different than what the incumbents are doing... They're a vertical. We'll never aim to be a vertical.