I am posting this information for anyone that happens to be searching for this information, via search engine or whatever means.
There is a lot of confusion via lower-level Apple employees as to whether or not the RAM and hard drive are user replaceable parts in the 2010 Unibody MacBook Pro. I have spoken with employees at the Apple store on the sales floor, both of which said that it would void the warranty for me to take off the bottom panel of the computer. Each of them asked a Mac Genius and the geniuses also said that it would void the warranty. I called Apple technical support and the rep on the phone said that she doubted I could remove the panel without voiding the warranty, but that she would forward me to the tech support supervisor just to make sure.
This is where I finally got the answer that I was looking for, because I was certain I was right based on information in the user manual (page 36) and on Apple’s website. I can absolutely confirm that the RAM and the hard drive are user replaceable parts on the current generation unibody MacBook Pro and it does not void your warranty to remove the bottom panel of the computer and change either of those parts out, as long as you do not cause damage in the process.
If you get trouble for this at the Apple store, ask them to call in the question to Apple for the correct answer. I’d also recommend that if you do decide to change your hard drive or your RAM that you put the original parts back in the MacBook Pro before bringing it in for servicing for multiple reasons. It would likely be easier to not have to bring up the replaced parts at all, completely setting aside the fact that Apple usually removes third party parts and sends them back in a plastic bag when you depot a Mac. Furthermore, if they do detect that the case has been opened, you could always bring up the fact that if you call in a RAM or hard drive problem, Apple gives you the option of them sending you the RAM/HDD for you to install yourself rather than shipping the Mac to them.
-Philip
