10 months ago
Last edited at 11:04PM on 2/20/2013
On most commercial jet types, most of the cargo hold is not pressurized; however, there's usually a section near the nose which is heated and pressurized for things like pets/livestock or sensitive cargo. But for the most part, it's unpressurized and unheated.
Edited to add: except in the case of the Boeing 787, which apparently heats the cargo hold with fire. (Okay, just kidding.)
Eric gave a good answer. However I would like to point out that if you need a detailed or specific answer, you should check with the carrier and find out what cargo options are available or what are the cargo conditions on the plane you are flying on. As far as beer goes, it would not be a good idea to put it in your luggage.