I apologize for not finding and answering your question sooner. Trulia offers logo branding mainly to large brokerages and franchises. If you are a broker and are interested, please access http://www.trulia.com/advertisers/brokers/ and complete the form on this page and someone from our team will contact you to discuss pricing options and so forth.
If you are an agent I recommend you access the link below and take a look at TruliaPro. It provides great exposure for your listings as well as your own brand.
Please let us know if you have any other questions.