In one of the biggest changes ever to its main search interface, Google is rolling out a new options system that lets you filter results by content type and publication date.
The options appear as a sidebar on the left of results pages. As with most Google features, this is being rolled out in stages, so you may not see it immediately (I haven't been able to directly access it myself; the screen shot was sent out by Google PR). The notion of seeing related searches on a wheel looks more fancy than actually useful, but being able to access a sub-category of results like reviews is potentially hugely handy. For another way of sorting results by date, check out this previously mentioned URL hack.