I have seen very few ecommerce sites using widgets or gadgets effectively. Apart from few examples like IRead application on facebook and Amazon widgets etc. It is not a difficult thing to build an app but more difficult is to build an app which becomes a success. This means an app which is liked by everyone.
Ebay with such huge traffic and product database is not active on social media circles as well as any other shopping and ecommerce sites. May be the reason could be due to the time and effort that need to be spent online and return from the same.
