If it's unsecure, then google would removed it. I guess. But this is clearly not the case. This is one of the most visited website in hungary.
I think i will contact google directly.

I mean your idea of automatically logging in to a website from a web page on click of a link is insecure. Google would not notice that as being an insecurity. It will find the page and list it.

You can't have a "hidden" page on your website that only you can access. Google will find and index all pages on your web space. I put one in, just to keep from using my Yahoo download bandwidth when I start browsing (instead of loading my full homepage). Nothing links to it except the homepage setting in my Firefox. Yet, I found it on Google while looking for something else.

I'm not going to read all the above posts and assume some people have already said this. A lot of schemers and crackers use "custom login pages" as a tricky way to acquire your password/login information. The reasons for their doings vary, however they're pretty much all out to get you in one way or another.

I strongly suggest avoiding anything but the pages on the companies login servers. So if you're about to log in to Yahoo.com, make sure you're on yahoo.com logging in. Same with gmail, hotmail, myspace...and so on.

Someone knows how to apply this script in the accounts Google APPS?

Wrong.

You can use a robots.txt file to tell search engines not to index it, or you can put HTTP encryption on it.