Adnan, for some reason, your post that is present on planet debian doesn’t appear on your blog at the moment (Sorry, no posts matched your criteria.). I would have commented there if that were possible. Anyways, I will give my opinion here, with different hats on.
(User hat on) The idea to have a similar start page on the different browsers is a nice idea.
(Web designed hat on) Some implementation details on your mockup are discussable, most notably the design in pixels (which doesn’t help for the vision impaired needing big fonts), the list of fonts to be used, and the border being part of the background image. Also, considering the targetted browsers, SVG could be a nice addition.
(Iceweasel, Xulrunner and WebKit maintainer hat on) The content at the bottom suggests the page is intended to be put online somewhere. Browsers start page shouldn’t require an internet connexion.
There should also be space for browser-specific icon and text. I’d really like to keep specific links, such as to bug reports and README.Debian (though the latter should really be htmlized). Speaking of these links, another one should be added some day in the future, to provide a link to a page explaining how users can help the maintainers (thanks to whoever came up with this idea during my BoF at DebConf).