There on the up here in London - a company called "Scooterman" is doing it properly (insurance being the big deal here in the UK) They seem to mainly use those mini motorbikes called "monkeybikes" that seem to take an age to dissassemble at the pickup point. London is pretty massive though - a folder would be cool but a trip out to the outer reaches of the south would take too long for most punters on a pushbike...
http://www.scooterman.co.uk/