I do, always and year round. My commute is 8km and I simply do not see or accept the need for bicycling clothing. I commute in -30c weather or on 40c weather, all in my work cloths. I sweat no more than my coworkers who have to walk 3-4 blocks after parking their cars. The key is know your pace. If you push yourself you will have problems.
Like the danes I also ride a city bike.
copenhagenize is a great site and something that I wish would catch on more here in the states. Been watching it for years.