Topsy is interesting in that rather than finding the best result due to external hyperlinks or having "one right answer", as Google and most other search engines do, Topsy instead relies largely on the number of times a URL is shared (or tweeted) around that specific keyword.
For example, while searching Apple on Google sends you to Apple.com, Searching for Apple on Topsy instead sends you to watch Apple's TV Ads for the "Get a Mac" campaign. You can guess that when the new ads debut, they are frequently sent around Twitter, pushing that link to #1.
Similarly, Topsy is influenced by recency, which explains why a similar search for Microsoft has articles on their Bing search product competing with Google rather than the vanilla Microsoft homepage you would get with Google.
But, as with Google, not all things are equal in the world of microblogging. If you have an account with hundreds of thousands of followers, thanks to a position on the site's Suggested Users List, you will no doubt have much more influence on how many times items are retweeted, and therefore, a much higher impact on Topsy. That means then that accounts like TechCrunch and Mashable, who are in the SUL, are highly featured, and other competitors, like VentureBeat and ReadWriteWeb, do not fare as well.
The impact of a big account can be seen both on individuals and topics.
Stories on TechCrunch.com are #1 on Topsy when searching for individuals like Eric Schmidt, Dave Sifry and Reid Hoffman, each a leader in tech, covered by the network. In parallel, Mashable holds the #1 overall position for individuals including Mark Zuckerberg., while ReadWriteWeb finishes #1 for Paul Buchheit.
Top Topsy Results for Eric Schmidt
Top Topsy Results for Mark Zuckerberg
Top Topsy Results for Reid Hoffman
Top Topsy Results for Dave Sifry
Essentially, Topsy is the delivery of "authority-based search" that Loic Le Meur was asking for at the end of 2008, but done so in a way that doesn't explicitly say so.
Top Topsy Results for Tesla Motors
On topics, you can see TechCrunch holds the top position on Topsy for Tesla Motors, as well as the #1 position for LinkedIn, #2 for Socialmedian and Google News as well as #3 for FriendFeed, with Mashable finishing #4 on that search. In each case the coverage of the company trumps the company's site or official comments.
Top Topsy Results for Apple's iPhone
In turn, Mashable holds the #1 Topsy result for iPhone, and the #3 spot for MySpace.
That's not to say there is anything inherently "wrong" with these results, but they are definitely different, and if Topsy should take off, the influence of larger blog networks and the Suggested User List on Twitter will expand further. Should search results lead you to the one true answer that delivers you a bland corporate page, or should they instead lead you to social news impacted by a large community?