Last week, Yahoo! launched OneSearch a downloaded application for your mobile phone that helps you search quicker on a mobile device.
The Yahoo Search Blog gives you examples of how it works. It currently doesn't work on many phones, you can see the list of carriers and phones that are supported over here. Plus Greg Sterling has a write up at Search Engine Land.
It does seem to be supported in multiple countries, based on the "Choose your country" drop down on the phone selection page.
Yahoo! has added that they are pulling back on the number of people who can download it:
Note: due to overwhelming demand for our cool new Yahoo! Go 2.0 beta, you may be placed on a waitlist of up to 1-2 weeks to get it (depending on your phone model). Register now for the beta — the sooner you do, the sooner you'll get it!