A couple of years ago I wrote about forums about Peru. It seems that there's been a move away from forums in general as people are becoming more and more addicted to Facebook. The group, Expatriates in Peru has over 2,000 members and lots of info about Peru and learning Spanish. If you don't know Spanish, you should start learning. It'll help you assimilate to the culture, and you'll be able to communicate easier. If you're looking to learn Spanish, check out Synergy Spanish, Rosetta Stone, and Fluent in 3 Months.
There are some problems with Facebook groups: they're not that searchable, information is quickly lost on the wall, and you can't see all of one person's posts, just to name a few. I honestly am trying to step away from both Facebook and forums since it's just too overwhelming. It's too easy to be connected to a computer or smartphone all day and I don't think it's worth it at all. However, those issues don't stop people from using Facebook. Hopefully in the future Facebook groups will get better.