Update: Ahhhh...So the Web page renderer for Safari and the one that Apple makes available to other apps registers differently. Thanks for helping solving that mystery.
Uh, oh. You remember that Google Easter Egg we mentioned earlier today? The one that allows you to browse within the app. Well, we got to, you know - thinking (for once) about this little browsing within the Google Mobile App thing (with some guidance from a commenter). Guess what. You aren't using Mobile Safari - as far as we (an broswer detection pages we checked) can tell. Does Google have their own WebKit based browser built into the Google Mobile App?
Or might Google be using Safari's Webkit engine and throwing off the browser detection scripts. We're sure someone out there is smart enough to help out.

Mobile Safari on the left vs. Google's iPhone browser on the right. The browser detection plugin sees different versions of Safari for each browser. Theoretically, they should be giving the same browser versions if Google's Mobile App is using Mobile Safari to render pages.
Google's Browser also has navigation buttons and the ability to open in new windows (see bottom). So what does this mean? It kinda breaks the ol' rules of the App store as far as we can tell.
Anyone else think Eric Schmidt should be slapping himself right about now?
Comments
Nope.
I tested this out by tweeting a link to the same browser detection page you used, and came up with the exact same results when viewing in Twitterrific Mobile. All WebKit browsers within other applications turn up the same result as Google Mobile.
It's quite a nice find, and the "open in new windows" feature is really great. I'm definitely using Google Mobile Search a lot more now.
dahhdahh
dahhdahh
"and the ability to open in
"and the ability to open in new windows"
Wrong. That button just opens the page in Safari.
User Agent
The user agent seems to be different whenever Safari is used to render a web page inside an app. In fact, the string "Safari" does not show up at all.
I think this is too much
I think this is too much speculation and second Johns opinion.
Netnewswire mobile produces exactly the same Output as your Google-App screenshot.
I can mail you a screenie if you want to.