The guys at work who introduced me to this are Linda (TreasureTrail925), Andrew (HereLooking4Cache) and Mac (MacDan1).
Andy has a GPS device, which is probably how he heard of this 'game'.
I have installed C:geo onto my HTC Desire. It's a free geocaching app for Android phones and it does seem very good.
At lunchtime today we went out to look for some cache's very near work again; in fact we could walk to them.