As much as i would like this...taken to a logical conclusion, not sure if it would help. Walk with me a bit, and see if this makes any sense (or not)...
1. A new search engine appears and focuses on "personal presence" sites - however a personal presence would be defined.
2. Google, bing, etc. begin crawling this new search engine, and its index of sites.
3. Users by default simply use google, bing, etc. to search for people...but how would google, bing, and other search engines resolve the conflicts of "which is the correct John Doe site?" between the results they've captured (such as on silos/walled gardens) vs results from this new personal site search engine?
Well, if its google, i suppose they'll use some signal like relevance. And, as i recall google uses link authority (big boys pointing to YOU gives you authority, which leads to "relevance" in the eyes of google)...which would suck because the big boy silos likely have a bit more "authority" by way of quantity of links, no? Unless i'm missing something, having another search engine - focused on personal sites - may not help the layperson find your personal site any more than current environment. Please someone correct me if my logic is flawed here, because my scenario is quite depressing.
(Let me caveat that I'm very much a proud supporter of personal websites, and would love having a new/additional "personal site-focused" search engine...I'm just not hopeful that it helps much.)