Instead of having that huge arrow to get people to install the OpenSearch plugin (or at least in addition to the arrow), you should use OpenSearch autodiscovery. When you go to a site with autodiscovery implemented, the logo box of the search bar glows blue. Go to Wikipedia and look at your search bar to get an idea of what happens.
Most users probably either don't notice or don't know what the blue glow means, so I can understand keeping the arrow, but you might as well add the autodiscovery too. Someone might do something nifty someday by crawling the web and scraping those autodiscovery links to build some sort of meta-search engine... that still wouldn't be as useful as Google, but it'd still be nifty.
I really really liked the yellow search bar, but I think you should make it point to something more useful than adding a firefox search. I personally don't use that for anything but very major searches(google, ebay, occasionally wikipedia). what if you used that bar to point to a sales special or something that can drive revenue or would be really appealing to users.
Most users probably either don't notice or don't know what the blue glow means, so I can understand keeping the arrow, but you might as well add the autodiscovery too. Someone might do something nifty someday by crawling the web and scraping those autodiscovery links to build some sort of meta-search engine... that still wouldn't be as useful as Google, but it'd still be nifty.
http://www.opensearch.org/Specifications/OpenSearch/1.1#Auto...