What gloves work well for winter riding? I'm starting to plan ahead for winter riding, and gloves are definitely high on the list.

What gloves work well for winter riding?  Are cycling-specific gloves the way to go for a flat-bar bike with index/thumb shifters?  Would regular winter gloves be good enough?

Another option I'm considering is buying some MTB gloves (full finger, some small amount of insulation) and wearing them inside regular winter gloves on the extra nasty days--letting me keep some protection if I need to ditch the thicker gloves (for repairs, or any other time the larger gloves get in the way).  Is this advisable?



Update 1: I should mention I live in Burlington, VT.  Lots of days below (and some well-below) freezing, and lots of snow :-D

Update 2: More clarification!  I'm hoping to commute in the winter on a fairly short route.  Initially (late fall) it will be ~4.25 miles, but hopefully by the time real winter sets in it will be about half that distance to a new location.  I'd expect my ride will consistently be 20-30 minutes, so I'm looking for something that will work well for a relative short while--but not worried about all-day hauls.
Bike-specific full-finger gloves are generally going to give you more dexterity, allowing you finer control over shifters and brake levers. They'll also have padding in the places you need it when riding. However, very few of these gloves will be warm enough for winter riding. 

The best solution I've found is to ride with a few layers of gloves, using full-finger gloves as the outer layer and thin gloves as the inner layers. On longer rides, you may need to pack several pairs of gloves and switch off as you need to warm up and cool down. 

Wind is your biggest enemy when riding in the cold, and your fingers will get cold. Options to prevent this include thicker gloves (like ski gloves), although these will make your hands clumsier; and lobster-claw gloves, which keep groups of fingers together. (Essentially, these are mittens with a split making you look like a Vulcan about to tell someone to "live long and prosper".) I haven't had to get one of those - yet. 

Here's what I use, and why: 



(click this image for a larger version)

Upper left: Regular cycling gloves

I'll use these, usually with glove liners underneath, when riding in slightly warmer winter weather. 

Upper right: Glove liners

These are about the thickness of denim, but can be rolled up like a small pair of socks. I usually take them along for that reason along, but they serve well under regular cycling gloves or even full-finger gloves. 

Lower left: Full-finger cycling gloves

I used to bring bulky ski gloves along before I got these. The full-finger cycling gloves  I have are made by Gore, and are super-warm (more so than those bulky ski gloves) and water-repellent. It's a bit of a squeeze to fit liners under them, but it works well. The disadvantage of these gloves is that I can't work my GPS or phone easily with these on. They're also overkill when I'm not riding, or if I'm riding slowly. 

Lower right: Conventional winter gloves

These are good for off the bike on a tour, or when the Gore gloves are too warm but the liners/half-finger gloves are too cold. These are also excellent for snowball fights.