Discovery of Voice Mail
There are two primary driving factors for the recent explosion in electronic discovery. The first is simply the amount of email people send each other these days, and the informality with which they do so. The second is the breadth of material available electronically. Electronic hotel door locks store information that can be used to track down who entered a hotel room and at what time. Microsoft Word and other Office programs store metadata that can reveal who edited a document and how long they spent doing so. One other avenue for discovery: voice mail. LLRX has an insightful article on the discovery of voice mail in litigation. Voice mail is typically recorded on a computer system (for a while, home computers frequently came with voice mail programs pre-loaded). It may be possible to get an audio recording of a voice mail, sometimes even if it has been deleted from the recipient's inbox. Keep in mind that the more time has passed between the deletion of a voice mail and your discovery request for it, the more likely it is to be impossible to recover (or at least too difficult to justify the expense).
(Found via the Trial Advocacy Blog).