There's a piece in today's Times law pages (may require registration) exploring the difficulties for companies and staff over using (or abusing) email.
Helen Brearley was dismissed as a designer for a Nottinghamshire shopfitting after using her office system to exchange more than 300 personal emails, many of the sexually explicit, with her lesbian lover over 15 weeks. But last week an employment tribunal ruled that her dismissal was unfair and awarded her £26,000 in compensation.
However, the decision was not saying that she was within her rights to have sent the emails, but that the company's policy was not clearly laid out.
...Her employer was in the wrong because she had not been warned that her behaviour was unacceptable. The difficulty for employers and their staff is over the interpretation of what is acceptable.
After years of these things happening, it is surprising whenever someone comes a cropper, but we're still clearly a society coming to terms with the public nature of what we believe is "private" material.