I assume by "its own page" you mean a standalone app, not a new tab in Safari?
If that's what you mean, I'm afraid you're mistaken. I remember when they added the ability to add a web app to your springboard, and I distinctly remember that they all opened in Safari, with the address and search bars at the top, back button etc. at the bottom.
A lot of web apps use javascript to hide the address bar (they just scroll down a single pixel). Could this be why you think they are their own app?