Well, I guess that really depends on who you know and how you use social media.

Most of my Facebook "friends" really are personal friends or at least acquaintances that I know for non-professional reasons. They are nice and often interesting people and I enjoy staying in touch. But I won't do business through FB and would consider it an incredible waste of time to follow status updates 24/7.

On Twitter, I follow several loosely connected circles of people. Some I consider friends, others I don't know and have never met. Shared professional or cultural interests is common. Keeping an eye on my stream through a good client gives me a narrow, personal and often useful heads-up about things that interest me.

Twitter, be being public by default means it doesn't have that intimacy that Facebook does. I'll follow someone if they're interesting, not because they're a friend.

But to answer your question, I find it fantastic for foreign language learning. Real, native speakers without travelling long distances.