The general idea of going to the people is good. But home delivery is tough for a drink with a retail of 2 to 3 bucks. THe driver tips would be cents not dollars. You'd also be competing with Keurig, Senseo, and all the other home single cup units. Granted, they are not espresso based. But man, that is a tough row to how. You'd need very high density customers for that to make any sense or the gas costs and travel time would kill your business very fast.
You could consider a mobile cart - sort of like those bicycle powered ice cream carts. That is an intermediate to an ice cream truck - it all comes down to location, location, location. Can you get to enough people so you are spending your time and money in transit?