I remember that someone asked Matt Cutts if Google could restrict search results to homepages. He answered that it's a good suggestion, but adding [-inurl:html -inurl:htm] to your query works pretty well.
Now you can restrict Google results to homepages, but only if you're looking for blogs. Google Blog Search has always highlighted a small number of blogs related to your query and now you can find even more blogs by clicking on the "homepages" filter from Google's sidebar. Google's definitions of blogs is vague and it's likely that any site that offers feeds is included in Google Blog Search's index.
"We've updated Google Blogsearch to make it easier to find blogs that match your query, instead of just finding blog posts. The blogs tool on Google search results filters your results so you see only blog posts. We've added a homepages option that shows a full set of blogs related to your query," informs Jeremy Hylton in a Buzz post. Here are some examples: [tesla car], [google], [android].
{ spotted by François Beaufort. }