The new google search is not available for all , but you can have a try the new Google , by a small hack
1. Open http://google.com in Firefox or IE(if you are on any regional Google like google.co.uk or google.co.in, click on the link at the bottom to go to Google.com)
2. paste the following line to the address bar and press enter
javascript:void(document.cookie="PREF=ID=20b6e4c2f44943bb:U=4bf292d46faad806:TM=1249677602:LM=1257919388:S=odm0Ys-53ZueXfZG;path=/; domain=.google.com");
it will not display any message, just after enter, follow to the next step.
3. Refresh the page(confirm that you are on google.com)
4. You are on new google now :)
[Via Sizzled Core]