In Designing Web Navigation, I have a whole chapter on integrating search and browse. The point is that from a user’s perspective navigating and searching aren’t different things. People just want to find information. And we know from berrypicking theory that people can switch their seeking strategies rapidly while looking for information online.
Google introduced Sitelinks in their search results back in 2006. These are automatically generated based on an analysis of the target site’s structure. Often, the links naturally reflect the main navigation options of the site. With this, the scenario is: you do a search on Google, and from the results can directly navigate the target site. (BTW, the introduction of Sitelinks is another good reason to make sure your site is well structured and has a meaningful navigation system.)
Recently, Google also introduced a site search features embedded right in the results list:
So now the scenario is: do a keyword search on Google, browse the results list which includes navigation from target sites, and now you can even do a keyword search on specific site. The line between search and browse is really blurred here. And that’s a good thing, I believe.