It's similar to 'Coin Unique' or 'Coin Extraction' depending on where it was made. Eddie Gibson is the godfather of such gimmicks but they are also made by others around the world. Apart from the £2/50p version, there are versions of other UK and foreign coins. Whatever you do, don't spend it - they cost over £30 brand new! See
http://www.emagictricks.co.uk/product_i ... ts_id=5642 for one example.
We've heard several instances where magicians have accidentally used their coin gaffs as ordinary coins when shopping, golden rule, keep the gaffs well separate and always check your change!!!