Trulia and Zillow use their own methods to get determine valuation and property status. Unless it is an active or recently sisting, it typically is not as accurate as having someone in the local market pull comps for you. Online sites gather market data and apply their own formula to come up with a value.
Here is what trulia says about their estimates:
This home has an offer but is accepting "Backup Offers". I have not seen this particular home, so I can not advise you on the condition. However, It is a short-sale. There are 3 other homes within 1/4 mile that are for sale that currently have no offers and 9 for sale within 1/2 mile. If you would like to see a list of surrounding properties, view this property, or want more information about submitting a "Backup Offer", please let me know.