By visiting this page, you can enter any term and get results from Google Profile pages. You can search for employees of companies, people from your hometown, people who went to the same school as you, people with similar interests, etc. This all works pretty well, but the problem is that since you probably don't know about these profiles, you're not using them and thus not filing them with all the pertinent information to make searching them useful.
Of course, for regular search, Google crawls other social network profiles such as Facebook's, but the Google Profiles could prove more useful because they contain information users want to share rather than information relating to a social network (with friends, clubs, etc) -- for now, at least.
The profiles also have nice little features. For example, if you put in where you grew up, where you currently reside and where you've lived in the past, Google will put a Google Maps badge on your page highlighting these areas with different color markers. Also nice is that when I went to edit my profile today, Google offered me the option to put an "I'm voting!" badge on my profile (which links to Google's election page).
On the About page for the profiles, Google outlines them as being a way to "present yourself on Google products to other Google users." But really, these are barely tied in with other Google products at all. Google Reader, for example, somewhat uses the profile information, but if you try to edit yours within Reader itself, you're taken to an entirely different Google Accounts personal information page.
I don't think it's a stretch to think that eventually Google will use these profiles to tie your online presence on all their properties together -- in fact, I've said this before -- but right now, the profiles remain a half-hearted attempt at something that could be useful. Yahoo's doing something similar, but at least it's trying to promote it.