I have been sent this link by two people today so I've got the hint - I'll blog it! Check out Atlanta's giant mapathon. A most interesting concept but some very worrying comments such as "this will create the most accurate map" (depends on your QA and QC surely? - how can they prove that?) and the assumption that mapping is black and white - "it's either there or it's not". So when does the pavement stop and the grass verge start, esp if it's all muddy and the verge has spread? What if someone decides the edge of the road is the kerb edge whereas someone else, perhaps on the other side of the road, marks it as the back of the pavement? How can you know everything has been picked up; or can you only hope it has?
I hate to be a pessimist here but, although this will give very up-to-date information, I doubt if it will be the most accurate, however I don't know what the comparator is. Nudge me someone (US side is good) for the next installment please.