I read somewhere here that it's to prevent GPS interference, as the GPS module is located right next to it.
Soak it in 99% Isopropyl Alcohol (or as high of a % you can get). It will help loosen the adhesive quite nicely. :)
Use 99% Isopropyl Alcohol (or as high % as you can get) to act as a lubricant for that stuck screw holding the left side of the home button. Like above poster said, I had the same problem with that screw. The alcohol works wonders! (I work in a clean room where lubricant is not allowed, so Isopropyl Alcohol is commonly used for this purpose)