Testing and development - is there a Facebook sandbox environment?

For us, we create multiple Facebook Applications, and use the keys to certain ones depending on what we're trying to do. Each app also has a development mode setting (I think that's what it's called now, it used to be "sandbox mode"). When in this mode, only the Administrator of the app can use it (either in Canvas views or for Facebook Connect functionality).

LinkedIn does not have any sandbox mode that we know of. Our LinkedIn integration app is coming out next week (likely), and for that, we took a similar approach to having one set of app keys for localhost or dev server testing and another set of keys for live site usage.

Hope that helps,
Alex