Growing my company down here in Chile has been an amazing experience. Like Ian's comment, I was also in a bit of a rut in the States. The international experience alone is critical to any good business - especially if you are from the US where the mentality is much more single-nation focused.
I've seen more opportunity here for actual business entrepreneurship - more than just an app or webpage - than I've seen elsewhere in the world. I'm a big fan of the business environment in Chile for both growing your existing start up or possibly ditching your brilliant idea in favor of an even better one you discover here!
The networking and mentorship will improve with time, but the LatAm networking is unlike anything in the States. In Chile, there's a good chance the person standing next to you is only two phone calls away from the President of a major company.
Certainly coming here I've realised that I ought to consider non-English languages (particularly Spanish) for web apps. Most folks here in Chile don't speak much English yet their middle class has a growing disposable income. LatAm's power does seem to be growing.
Also some of the companies in our rounds (Round 2+3) were quite inspirational - water purification, classroom neuroscience, human-waste->fertiliser solar cookers, solar powered food cookers, wind farms, safe remittance systems for migrant workers.
I'm most curious to see what Round 4 brings (quad-copters from one I think). Accelerator high-tech is more than Web2.0.