This is not a Rumor. It is rediculous, true, but it is correct. I found this thread because I was researching this issue. I have a new 2010 model 15" Macbook Pro with logic board issues. The video keeps hanging and I have to power it off in order to do anything.
So, I took it to the Apple Store and they had to order the part. 7 days later, they call me and said that because I have upgraded the hard drive and RAM, they are going to void the warranty. I raised hell until the guy told me I could come up and get my macbook, put the stock stuff back in, and bring it back up. We had to do it all shady and under the table so that I didnt get screwed. This laptop is less than two weeks old. If I had it to do over again, I wouldnt but a macbook if I would have known how they are about the warranty.
I am a Network Engineer with 11 years experience, I think I am capable of replacing a hard drive and RAM without messing something up, Oh well. I am gritting my teeth and getting it fixed, but this is the last apple product I will buy, and I have an IPhone, two Ipads, and this was my first Mac...