Is there a common nginx conf for Drupal 7 sites?
The main problem that Drupal 7 has with nginx is that Drupal is designed for Apache, and so many modules assume that Apache is installed (and you will always have a little blue entry on your "Status Report" that tells you that you can't use Upload Progress because mod_php isn't installed — annoying).

That being said, thanks to perusio and others, many modules have been created that deal more with nginx and tap into its functionality well. So far, I haven't run into any problem with nginx that would have been fixed by Apache, and nginx is far faster and has a much lighter footprint. This is shown by many benchmarks, but it's also my experience. It also has better integration with php5-fpm, which also outperforms mod_php.

As Drupal develops, it is becoming more backend agnostic. You can see this with 7's database abstraction layer that allows for more database backends, and so I assume that future releases will be designed with other web servers in mind.

So, there are no pitfalls that I've seen at all. You just have to pay a bit more attention to what some of the modules do, or at least what they say they do. If they mention .htaccess files, then make sure that you have corresponding entries in your nginx files that do the same thing. I haven't actually seen a case where nginx fails with a proper configuration.

Perusio's nginx configuration is absolutely amazing, but it takes quite a while to get through it all and understand it. You WILL need to customize it for yourself, and you might run into some problems that you'll need to fix if you use non-standard setups for things like imagecaching or advagg or some others. It also assumes that you're using more than one php-fpm pool. So you'll need to go through and pull out what isn't needed. But it is worth it to take the time to go through it all because you'll learn so much about how nginx works.

I've also ran into several errors with my nginx/drupal sites because I have a tendency to use php-fpm 5.4 or 5.5. The errors have nothing to do with nginx but with Drupal functions themselves as Drupal is just really finishing a transition to requiring php 5.3. If you look around the issue queues, however, you'll find several patches and other solutions to fix modules to work with newer versions of php.

At the end of the day, I would recommend that anyone who is starting with a fresh server use nginx instead of Apache. It's just better.