Canonical's Mark Shuttleworth confirmed That is looking to replace Firefox with Chrome in Ubuntu. That Shuttleworth said he is a big fan of the browser from Google & confirmed That there was discussion on the feasibility of Chrome (or Chromium) Replacing Firefox in Ubuntu 11.10. That did not Happen and the switch will, in all probability, not Happen in Ubuntu as well 12.04 Because it is a Long Term Support (LTS) release.
So, it may take one year for Chrome to replace Firefox, but Shuttleworth said That it is a real possibility That We May see Firefox being replaced in Ubuntu 12.10. However with the pace of Chrome's development and Mozilla adopting an accelerated development cycle for Firefox recently, thing Could change a lot in a year.
Shuttleworth said That one of the best thing to have Happened for Chrome on Linux has been Chrome OS. Because Chrome Chrome Basically the OS is running on a Linux, Google has invested a lot in optimizing the performance of Chrome on Linux. That has resulted in Chrome on Linux outperforming the other platforms - Mac & Windows.
Whatever is the the default browser, users are free to install the browser That suits Their need, just like Chrome users do today. So, in essence choosing Chrome / Chromium as the the default browser Will not affect anything. Will it simply be an acknowledgment of the progress That Google Chrome (or chromium) has made in the last two years.