Um, rust isn't really that big of a problem unless you have a lot of blemishes in a steel/chromoly bike.

I am lazy, but anal and what I do is use a wet towel to wipe everything. Seems a lot less work then soap and water, but anything works, really. Just avoid high pressure or soaking of bearing areas: bb, headset, hubs, etc.

You can wax it using car wax or something to keep it clean longer. Works well for me. I can usually just rattle my bike around and the dried mud falls right off when I have a nice layer of wax on the bike.

Make sure to relube everything afterwards.

Good luck.