That website is optimized for WebKit browsers, so no, It will not show in IE9 Mobile. Perhaps there's a way to force it, I personally don't know. I'm pretty sure that it would not work correctly even if you did. WebKit is the Internet Explorer 6 or Mobile Browsers. I don't even know if that site renders correctly in Opera Mobile. Guess I have to check that some time...
You can't just go to the page and have it show it to you. It checks your browser signature and decides what page to display for you based on what browser you are using. Since WP7 uses IE, it serves up the worst version of the page. It's similar to how Facebook's mobile site gives WP7 the crappy page while WebKit users get the full mobile HTML5 site that functions like an application instead.
That's a matter of [web] developers support, really. As WP7 marketshare increases, it will be harder for developers/companies to do that without alienating a lot of their customers. Personally, the best solution would be for Google to release a GMail App for WP7 similar to what they had for J2ME/BB devices and what they just released for iOS.
@ OP : My comment about Hotmail not archiving was just random uselessness in response to you letting us know that you hate Gmail... More of a "see what I did there?" comment than anything. Me being fecetious