When it comes to troubleshooting hardware issues on any computer system, if you plan on getting your hands dirty and messing with the interior of the system, or if you plan on gauging heat or noise issues, then it helps to know where items are located under the hood. To help with this, the folks over at iFixit have developed an extensive library of high-quality teardown guides for many of Apple's products, and have just added one for the new 15-inch MacBook Pro.
While most people (especially new owners with systems under warranty) might not have a reason to open their systems and access items on the motherboard, knowing where items are located can be exceptionally useful in determining if there is a problem, especially if the computer gets particularly hot or starts making odd noises. For instance, in the new systems there is a relatively large controller chip behind the I/O ports (suspected to be the Thunderbolt controller), unlike older MacBook models that do not have this component.
Again, to gauge what components may be making any odd noises or causing heat it helps to know where they are in the system. The iFixit guide shows the placement of items in the new systems, but also shows some of the assembly, noting in particular an excessive amount of thermal paste used to connect high-heat components to heat sinks. This may not cause any problems, but excessive thermal paste can actually reduce the heat transfer efficiency to the heat sink and potentially result in overheating and failure.
Keep in mind that this guide is for the 15-inch MacBook Pro, and there may be significant differences in placement of components and latches between this model and the 13-inch and 17-inch models. Also note that while this guide does show you the component layout, it is not a full take-apart guide since it does not go into detail on specifically where screws and latches may be, and what forces or any other cautions might need to be applied when removing them, so it may be best to wait for a full guide that includes these details if you are not familiar with working on Apple's systems. iFixit usually comes out with separate guides for individual components in a specific Mac model.
The last thing we should mention when discussing the disassembly of any system, of course, is that if you take apart your computer you do so at your own risk, and you may void your Apple warranty. Make sure the problem with your system that you are addressing is not covered by Apple before you attempt to repair the system yourself. Sometimes just opening the system may leave marks that will indicate to an Apple technician that you attempted to service the machine, which may void your warranty even if you did not tamper with it further.