In case you tend to skip the Tech forum here, I thought maybe it might reach a broader audience who may be using Twitter.
You CAN be sued for what you write on Twitter.
If you don't have a lot of time, I recommend scrolling down to the last few paragraphs of the article.
Also, please remember that Google 'caches' pages. Within less than 48hrs sometimes. So, something you wrote on Twitter two months ago CAN still be seen.
The general rule of 'safety' is two-fold:
1) if you write on the interwebz, it's not 'safe' and you don't have a 'right' to it ( generally )...people can forward and print out your emails and you never even know it's happened and by the time you have, it could have been forwarded to 500 people in a matter of seconds ( literally )
2) if it can appear between these two tags :<html> and :</html)...minuse the colon...it is, technically, the start and stop tags of any web page and can be, unless you own the site and server the .html file is hosted on, it's a web page and is probably being cached by Google...
in the case of emails, a decent encryption program may be something you familiarize yourselves with, then use but in savvy hands, they're not all particularly hard to deal with from what I hear..
btw, if you feel your emails should be 'private', your ISP ( the entity you get web service through ), does not necessarily agree with you and may, in fact, actively track how you use the web, log it to a db, and periodically turn it into authorities or advertisors...
just thought i'd mention it...