Most modern software offers users dozens of ways in which they can customize and optimize everything. The average person probably does little more than pick a pretty background photo or font before abandoning the options menus forever, though. So it's potentially quite important that Bing will be included as a standard search option in Firefox 4.
At the moment, Firefox users who try to look over their search options will only see Google, Yahoo, Amazon.com, Answers.com, Creative Commons, eBay, and Wikipedia as alternatives. Then there's an ominous "Manage Search Engines" line that very few people will click.
In Firefox 4, Bing will be listed right after Google and Yahoo, instead.
A post on the Mozilla Blog announced and explained this change by stating, "Bing itself offers a user experience that we think users will find valuable, and with its significant rise in popularity over the last year, we will also be including Bing as a general search option for English language users."
A post on the Bing Search Blog then chimed in, "We hope you enjoy this new choice for your Firefox experience and we look forward to hearing your feedback on how we can continue to improve."
It should be interesting to see if Bing's market share rises as a result of the move. One important thing to remember is that Firefox is caught up in a tough fight with Chrome.