Not "kit" as in gear (or "KITT") but cycling kit - clothing.
I've been thinking about commuting clothing for a little while now. Mainly because Baltimore has entered the "do people actually enjoy living in this kind of weather?" part of the year, where it's unpleasant to walk outside in the morning and gets worse all day long. I'll admit it - I'm a wimp when it comes to humidity. I come from the semi-desert North/Central California (east of Berkeley) originally, and when it gets hot there it gets dry. I love that feeling. Walking out at the end of the day into a 95 degree oven and being baked. This whole parboiled thing is for eggs.
During the cooler months here I commuted in my work clothes. I ride an upright bike with a chain guard, so riding in slacks isn't a problem. Since I use full platform pedals, the shoes aren't an issue either. Finally, the ride is a whopping 1.5 miles each way, so it's not like I need the padding of bike shorts to preserve my derriere.
Back in CA, before I moved, I was a spandex warrior. It took some getting used to because while I think I can honestly say I have the lower body for bike shorts I certainly DO NOT have the upper body for a jersey. Snug and gut are a bad combo. But I was also doing 20-30 miles a day on my ride home, much of it in mid to high heat (85-105F) so semi-technical clothing was in order.
Now I ride in normal shorts and a t-shirt. The shirts I use most of the time are the old (now) "HHCMF" (Happy Hardcore Commuting MFs) that I got years back on Bike Forums. They're handy, being ANSI lime, and bike friendly with the "Ride to work/Work to live/Live to ride" triangle on the back. On a commute as short as mine, with an upright bike like mine, and going the pace I go (average around 11 MPH) I just don't see the need for anything else.