In my personal experience, the answer is simply, "No". I've been active within my real estate market for > 20 years, can "sell ketchup Popsicles to women in white gloves", and have owned/operated a lead-generating call center employing 50+ people, an investment bank, and have served in every single capacity as it relates to real estate. In short, Trulia's "leads" are essentially people who click a link (not knowing what they're clicking upon) which results in a re-directed phone call to you. They have to stay on the phone while it's patched-through to you. My experience has been that > 90% hang-up prior to being patched through. The other 10%? Well, they're looking for rentals, properties well under the threshold you set with your Trulia marketing rep, or are otherwise "not interested". Of those who elect to leave a message during the 4 hours per day you're not available to answer the phone, they either comprise the aforementioned or they are recent buyers looking to know what their home's current value is (so as to reassure themselves the got a "good deal"). Listings? Forget about it! I've been working 3 owners for over 4 months...they're not really sellers. Buyers? Forget about that too. They either have representation and are under the misconception "you" are the listing agent or they're just looking to see what the market (that they can't see on Trulia) has available so they can take those properties to THEIR agent. Duties owed when meeting with the prospective buyers? Done! Interested parties in "My" listings (as directed by Trulia)? Done. Ask yourself this: If a prospective buyer already registered with another agent calls you about a listing held by another agent....how do you respond? More importantly, how do YOU get paid?
It's AMAZING this type of marketing could yield any fruit. I'd pay $1,000 to watch bugs engage in unsavory relations; however, I would (no further) pay $0.10 for the leads I've been provided during the past 4 months from Trulia!!
Just my $0.02 (for which I've spent $4,500+ up-front); but, I'll offer that to ANYONE for free. I've fully vetted this medium of marketing and passing out flyers or sky-writing would (presumably) be more economical. :(