Highly spill resistant is more like it. I own this product and I have managed to spill using it, mostly do to user error (the day someone invents an idiot proof travel mug I'll be all set).

It works by the user depressing the grey button in the center, you can sort of make it out in the picture, which pops up the round silver bit and allows coffee out. To close you press down the silver ring. It also comes with a more traditional screw top (not pictured), which when used automatically depresses the silver ring.

It works fairly well. With the screw top and ring depressed you can hold it upside down and it does not leak.

It holds about a cup of coffee and keeps it very warm. I got mine for about $20 from a neighborhood hardware store, so shop around.

The problem in use is that if the screw top is not firmly screwed in the silver ring may not automatically depress and then it will leak. This is an end user problem, but in the morning before coffee it is pretty easy to forget to give it that last little tweak closed.

In addition, should you pour boiling water in to preheat the travel mug, and then shake it up and down to demonstrate its amazing non-spill qualities, the force of the steam will blow the top off sending scalding steam everywhere and making you look like the idiot you are.

Steam is powerful stuff. Don't mess around with it kids.

I have a Starbucks mug that is eerily familiar.
I hate it, though. Spill-proof also means keeps-everything-at-scalding-hot-temperatures.

Thankfully, after burning myself on hot coffee more often than not (Pavlov, HAH!), I'm starting to lose sensation in my upper lip and the tip of my tongue...

I have a truly spill-proof Thermos-brand travel mug. It works by having a drink-through screw top that gives you access to your drink with a 1/4 turn. It's a bitch to open if you pour boiling water in, close tightly, then wait an hour to open it. Keeps stuff hot or cold for several hours, though. As long as you remember to screw it closed when you're not drinking it's genuinely 100% leak- and spill-proof. Of course, that didn't stop me from putting it *inside* my laptop bag without the lid fully closed. Dumped a lot of coffee directly into my computer. Didn't cause any damage to the computer but the bag's totally ruined.
http://www.amazon.com/Stainless-Steel-Leak-Proof-Travel-Mug/dp/B000FDP13I/

I'm drinking out of one of these as I write. I got it for Christmas; I'm not sure I would have purchased it myself. It's quality stuff, even if it's a bit small for a 4-8 cup-a-day kind of guy.

It doesn't affect the taste much at all, which is more of a problem than you'd think with higher-end travel mugs.

I'm not sure it's 100% spill-proof--obviously if there's coffee in the cap when you close the cap, that's gonna get all over your crap, but I regularly toss it into my bag along with my laptop, moleskine, and textbooks without a problem.

I'm sad to relate, however, that indeed, the button is in the top.

I have several Starbucks mugs that, when closed, are pretty spill proof. I'm a klutz, and had one mug fly out of a pocket in my backpack yesterday in the library, and it didn't spray water all over the instructional materials collection. It also didn't spill water everywhere when I knocked it over during a test today. It did make a very loud noise in a very quiet room though.

The mugs I have are not perfect - they don't keep liquids hot for extended periods, but they're good enough for what I need, and I usually grab them on sale so they're fairly inexpensive. I like that I can put milk and sugar in my coffee, put on the lid, and then shake it to mix it in, without coffee flying all over me. The stir sticks are never quite long enough and I always end up burning my fingers.

The Starbucks spill proof ones are pretty good.

Won't look twice at the cups which have only a slider flap or open hole. That's a joke waiting to happen.
That style is going from kitchen to garage.
Not car, or roller coaster.

I've dropped $25 Starbucks cup models with them fully loaded, and no worries.
Hydrodynamic Shock when dropped isn't pretty in cheap ones.

The ultimate that want the 17oz-3 cup and want it hot all day is Starbucks thermos with screw on cup, which then protects the inner push button valve and stays clean.
Even fits snug in the truck cup holder.

Plowing snow in the Bobcat or truck, the thermos rides shotgun all night and stays good and hot. This is rough environment.

Adding cream and sugar should be done first, then coffee.
Pour out load to be nuked for 1 minute, more or less, then reload cup or thermos. No SHAKING needed.
Thermos is now preheated, and reload stays hotter.
1/2" air gap is best.

The Monster Garage Pro-Series.

The Contigo mug is much simpler to operate (the button is more obvious) and looks a bit more stylish too.

http://www.wejetset.com/store/item/65

I have a 'Brewing Market' branded version of this mug and it's great. With the button engaged, and the screw top lid in place, it does not leak.

The real beauty of this mug, though, is that it doesn't suffer from the vapor lock that so many other insulated mugs do. Many mugs have such a small drinking hole that they're near impossible to drink from without burning you mouth when the hot drink gurgles out. Not this one.