Trulia receives feeds from many sources, and a lot of times, they don't know who the listing agent is. So with those agents, they categorizes them as 'Unclaim Listings'
If you are the lising agent for a certain property, then you should go ahead and click on that 'Brand It' button. It will put your Trulia profile on the listing.
Hope this clarifies the issuse. You can also look at my profile. At the bottom, you will see my listings =- that's after I 'brand' those with me.