Search Google.com from your iPhone (or Android or webOS device) and notice the brand-spanking new Options drop-down on the top right. Tap it a list Google's Mobile Blog says:

Finding the exact information you need sometimes requires filtering and refining your search results. Earlier in the year, we launched a collection of tools called Search Options which enable you to easily and quickly do this from a computer. Today in the US, we are making Search Options available on Android/iPhone/Palm WebOS devices so that you can slice and dice your mobile search results as well. For example, suppose you are shopping at a store for a camera, and you would like to see what users have been saying about a specific model within the past week. You can do this simply by searching for the name of the product. Then, on the search results page, use "Options" to filter by "Forums" and refine further by choosing "Past week".

Let us know how it works for you...