I think at this point most of us are probably pretty careful about what we post to our Facebook pages, Twitter feeds, and Flickr accounts (recently humiliated political figures notwithstanding). We've known for several years now that a quick Google search can show employers any old photos or opinions floating around out there in the Interwebs, and likely most of us have tried to remove those that we're not proud of. So I found this Forbes post from Kashmir Hill interesting: "Now Your Embarrassing/Job-Threatening Facebook Photos Could Haunt You for Seven Years."
Here's the gist: Background check company Social Intelligence Corp. has gotten the government go-ahead to use people's Internet activity, postings, and photos as part of their screening process for employers. While this may not raise many eyebrows, what might is that Social Intelligence Corp. then saves any potentially hinky info in your file for seven years. Just another reason to think twice before you tweet.