When you list your property in the mls it direct feeds to all Broker websites. Coldwell Banker, Redfin, Windermere, The MLSonline.com, John L. Scott, Zip Realty, etc.
Trulia is not a "Brokerage Site" nor is Zillow. Your listing "can" show on those two sites, but it is not automatic as a result of putting your home "in the mls". Some Brokerages have a direct feed outside of the norm, but that has to be instituted by the Brokerage, vs the mls system. Your agent can also cause your home to be in Craigslist and many other sites, as an individual effort.
The disadvantage is that without a direct feed from the mls, there is not an auto update when the price changes or the property is sold. So if you manually "put" it in a lot of places, make sure you know where you did that so you can do the manually updates.
Any Brokerage site showing property via a direct feed from the mls will have automatic updates from one source...others...not.... more