Ubuntu desire to go Windows-way is not even latent any more. In 9.10 they've just added Multisearch add-on for Firefox 3.0 that replaces default Google search with customized one. Search result page is now missing GMail, Calendar and other links but instead includes some advertising, luckily raw text only. Still, 'adware' is the only polite word applicable.
This bug is listed in Launchpad already. I personally do believe that the problem is not technical but the bug is in maintainers' minds. Hope I'm wrong.
To heal this behavior,
switch to Arch disable (or uninstall) the Multisearch add-on:
Tools -> Add-ons -> Multisearch 0.0.1 -> Disable
You will get pure Google search from both Search box and address bar, and every new tab will open blank as in good old times. However, default home page (http://start.ubuntu.com/9.10/ in my case) still has the custom search box. Fix it:
Edit -> Preferences -> Home page = about:blank
All done, enjoy.
Alternatively, say, if you definitely need Multisearch add-on installed and enabled, go to about:config. To customize searching from address bar, set
keyword.URL = http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&gfns=1&q=
This is default for Firefox 3.0 on Ubuntu 9.04. Make sure is says /search, not /cse -- the latter stands for Custom Search Engine. gfns=1 is some sort of 'feeling lucky' bit and can be removed. Actually this would be sufficient:
keyword.URL = http://www.google.com/search?q=
To add regular Google search engine, there is an add-on. Set it as default and enjoy, again.
Ok, Ubuntu 9.10 is still in alpha, but the tendency of including adware is so much disappointing.
Package maintainer's comments: http://www.asoftsite.org/s9y/archives/162-What-is-this-Multisearch-thing-in-my-Firefox-about.html