Not really, but Apple told me when I asked that any damaged caused by installing the new HDD would not be their responsibility. Also, if something happened the new HDD Apple is obviously not responsible. All HDDs come with their own warranties though.
Really, installing a new HDD is very easy. Ten minutes at most for physical intstall. The most important thing is having the right screwdrivers. OWC.com has a great HDD install video + they sell a perfect tool kit for the job as well.
You don't want to over tighten the screws when putting the bottom plate back on. Just be gentle and wise. It's fun
.
I installed a Hitachi 320g, 7200 rpm recently. I took a deep breath and took the plunge. Glad I did. Also upgraded the ram to 4gb. You can do it too!