I saw this discussion about post hiring checks with the previous employer and was just curious how common of a practice it is for a new employer to call the most recent previous employer to check on you. I have no particular concerns regarding my background but thought the practice was slightly "big brother". Have you ever been in that situation and how are outcomes handled?
As a general rule of thumb, the larger the company you are being hired by, the more likely that this check will be done. Most small companies seem satisfied with standard reference checks from peers or former managers, but are not as concerned with an official notice from a former employer. Large companies with more processes in place are very likely to confirm employment dates with your most recent employers.
Assuming that you represented your past employment accurately, the outcome would be that you have nothing to worry about. If you misrepresented your background, you will probably see an offer taken back.
Where this becomes tricky is that a candidate would not want a new employer to contact his/her current employer before an offer is accepted conditionally, yet if the check is done and is not to the satisfaction of the new employer, you could be left in a very difficult situation (no new job, and having to explain to your current employer about interviewing for and accepting a new job).