I don't know how people do it, I thought it was an interesting novelty experience for the first 5 miles and then after that I was ready to be done. Maybe a commuter bike with fenders would help my experience, but that won't help with rain in the face, or wet shoes.
I will say that my jacket I got for my birthday was absolutely sick! http://amzn.com/B004UEZRFU Water bounced right off it, and I was far less sweaty inside the jacket than I would've been with a more conventional jacket. I wore it in 10 degree warmer and non-wet conditions on the way home and first I started with unzipping the sleeves, but I wasn't sure if I could get the sleeves off while I was riding, turns out that the last bit of zipper unlatched itself, and it was relatively easy once I put a foot on the ground to actually take off the sleeves and stuff them in my bag without taking the whole thing off. It's no go on putting it all back together though, heh.
Still despite my excellently performing Jacket, I'm not sure I'll be a big fan of commuting in the rain. I will end up using the jacket for cold or potentially wet conditions, but making 12.5 miles in the rain, well that's not going to happen unless maybe it's a lot more tropical. I'll try again in the spring. Until then Northern California is wet off and on, so I should be able to get some dry rides in here and there.