bene313 - usually your local council is the first call you should make and they should put you in touch with a nominated bee swarm coordinator who would usually be aligned with the local apiarist club or society. This poor guy will usually be run off his feet during swarming season. Swarming season for bees is during the spring and early summer. Swarms occur when the queen of the hive is getting a little older (weaker) and/or the hive is getting overcrowded and the beehive actually splits itself into two. Half the bees together with the existing queen load themselves up with honey then nick off (swarm) looking for a new home. The remaining bees left in the hive will have started to breed up a new queen for the remainder of the hive from the eggs laid by the old queen. The bee swarm will form a cluster as they have on your old couch, they may be transiting and bee scouts may still be looking for a more suitable location - letterbox, hole in the wall, compost bin where they may decide to settle and continue to do what bees do.
Beekeepers will take steps to prevent their bees from swarming by replacing the old queen with a new one (for example) - but steps can be taken to prevent swarms but they still may swarm, and if they do, the existing bee colony can can loose 20 or 30 thousand bees - not good for honey production. There are also feral swarms from wild honey bees.
So chances are that your swarm may move on to another location in a few days - you wouldn't want them to make a new home in a wall cavity of your home as they will start filling up your wall cavity with honey!
The swarm coordinator will come over and place the swarm in a container who will pass them onto a beekeeper who will use them and put them to work as a new colony.
You may like to do a search for beekeeping clubs within your area as some will come and collect your swarm for nothing - usually a beekeeper as he/she gets a new colony for free or the poor swarm coordinator who will usually have a family and a regular job who will come and collect them for a fee.
good luck
wombat
PS - yes I like bees, I reckon they're cool.