To change the thread off of clothing a bit, I'll add some other things I've noticed since I've started commuting.
Since I'm still pretty new to the whole cycling thing as well and I wasn't getting any real exercise prior to commuting, I definitely feel a lot better in the morning after my ride in. (thank you Captain Obvious!) I used to just walk a mile from the subway to work to get something in.
Also, the people at work were pretty surprised that I was riding in when it was cold out. It was a mild winter, but you know how people are.
I have noticed how easy it would be to make cycling a little better in NYC, some simple things would really help out. Just a series of simple things, most of which groups here in NYC are already campaigning for. It's just unfortunate the city does so little, and so slowly. I'm a big fan of mass transit as well, we have good infrastructure here but things like bus lanes and bike lanes are so often ignored by the cars and trucks.
On the bike front, well, I was using my brother's old mountain bike in the beginning. I put on a rack, el-cheapo fenders and 1.5" slicks. A pretty nice ride, but it felt too small for me (probably was). It did the job, but I wanted to try something else. I picked up a Gary Fisher Tiburon S, 700cx32 slicks on it now, fenders and a rack. I'm a bit mixed about it, I like the ride better though and it's my current commuter. I'm not too keen on the front suspension, I think I'd rather do away with it but I'll leave that for later. Back in college I used an old Peugot 10 speed, nice old road bike I picked up for $2 in NH. I had it ridable, but still needed work. I may try to resurrect it one day, but I already have 2 bikes taking up space. Mountain vs. hybrid, I like them both. I think I like the idea of a more touring oriented bike, I'd like to start doing some touring this spring/summer. We'll see how the Tiburon holds up on my first tour (self-supported with some pals, easy pace, should be good fun.)
I've driven in NYC enough to realize traffic can really suck. Riding my bike around, well, traffic can really suck. There are a few places on my commute where I'm stuck on a 2 way road, buses and cars parked on the right, 2 lanes of cars jammed beside me going my way, and no path to squeeze through them. I take the lane when I need to, that's not the issue. It just reminds me how silly it is to drive around the city.
On a final note (for the time being) I've noticed how easy it is to commute in from where I live, I can't believe I didn't start doing this years ago. I can see the obvious barriers to entry here in NYC, most people think it's totally unsafe. Bike theft is pretty high, cagers (I like that term... first time I saw it was here on the forums) can suck, and it's not always a bike friendly town. But it would only take a few more incentives to get more people to ride in. I'm just a convert though, and I work at a place with good bike racks in a good location so it's easier for me.