Asus is the only manufacturer I know of that offers a seamless international warranty.
Dell offers intl. warranty but it is applicable only in one country at a time, or region-wise (think Asia-Pacific, the Americas, Europe). A system bought in one geographic location can have its warranty applicable to another region by transferring the service tag number. This is automatic if you pay for a three year+ warranty up-front, otherwise you have to do it manually every time you go to a different geography.
PS: This is only applicable to Home systems. Business systems do not provide you with the option of transferring your service tag when you travel. To get international coverage on a business system you'll have to buy a new warranty wherever you go.
I have no information about other brands (Acer, Lenovo, HP.)
Other notebook manufacturers do not offer international warranty (read Alienware, Gateway, etc.) You will, of course, be able to get technical support for your system within the warranty period if you call them up, but spare parts will not be shipped internationally, and neither will any technician come over to replace them. You will have to send your system to the country where the warranty is applicable in order to get it serviced.
Clevo resellers: I'm not sure, but I suspect they don't do it either. Could be wrong, though.