Ahhh... Mercury. You magnetic, relative planet moving as quickly and erratically as the messenger god you were named for.
Mercury is the god of communication, travel, merchants, thieves, gamblers, ambassadors and alchemy. He was originally god of the trade in corn. He is said to be the father of Pan. His mother is Maia. His festival is the Mercuralia on 15 May. He was very popular with the Celts, who equated him with a number of their deities. Mercury carries the Caduceus, the symbol of immortality and the art of healing. (Text from The Yew Tree, a site by Yvonne Aburrow.)
What the planet rules (astrologically speaking) is very similiar to the qualities of the god. And when a planet is retrograde, all that it rules gets a bit skewed. So during Mercury Retrograde you'll see more car accidents (transportation), there are often problems with telephones and computers (communication), and we all seem to be wandering around mucking things up and acting generally as if all of our synapses are not firing properly (wit).
You generally do not want to sign a contract during a Mercury Retrograde. Often something will go wrong. It's also a bad idea to start a relationship during MR, as it will most likely crumble quickly. Conversely, break-ups initiated during MR rarely stick -- which is fortunate, since at this time many couples have bitter disagreements due to miscommunication.
Good luck, gentle readers. This will be over on November 1st (All Saints Day).