Google is playing with the interface for quite some time now. People were just randomly chosen for checking the new one. So one time you could have it, the other time it could be the old one again. You can check the new one for yourself by going to
google.com and adding this in the address bar: javascript:alert(document.cookie="PREF=ID=fb7740f107311e46:TM=1142683332:LM=1142683332:S=fNSw6ljXTzvL3dWu;path=/;domain=.google.com").
If you want to try it on local Google sites just change the domain at the end to the one you use (like google.be or google.co.uk, ...). Press enter so you get an alert box. Press ok and type in a search in Google.
Personally I prefer the old interface.