For most countries the guide separates out proper tipping for restaurants, hotels, and drivers and guides. There are also quick explanations about whether you should be tipping in dollars, local currency, or something else entirely. Feel free to tip in dollars in places like Indonesia or Vietnam, but make sure that if you're going to try to pass US currency in Canada you're using paper. Try to avoid using dollars to tip in Australia and New Zealand, even if they'll take them. In Singapore you'll just get screamed at by cabbies if you try it.
Where the guide gets really useful is in the "PS" sections that are attached to many of the entries. Those blurbs cover a range of topics, from not getting fleeced to where to expect poor customer service. Actively dissuade squeegee-wielding Mexican boys with a shake of the head. Don't bribe Filipino cops with anything more than about $4. Don't expect anyone to go out of their way to make you comfortable in the Caribbean. And the Japanese are indeed very polite.
The good folks at Traveler have even gone so far to create a printer-friendly PDF that you can carry with you. Or, alternatively, that you can print out multiple times and distribute to any European friends you might have.
[Photo: Conde Nast Traveler]