It is popular to think of the word “gospel” as referring primarily to one of the four writings of the evangelist regarding the life of Christ. If one is seeking a Pauline definition of the word we usually see reference to 1 Cor. 15.1-8. I think there is one definition that is usually ignored (exceptions include most new perspective writers such as Dunn and Wright) that is found in Gal. 3.8:
And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, “In you shall all the nations be blessed.”
We cannot ignore that one very important aspect of the gospel is the universal Abrahamic blessing that is extended to us who are not Jews. Although modern scholarship has been emphasizing this point more and more it does not seem that the church has grasped it as strongly. It is essential to the content of the gospel that the nations would be welcomed into the people of God through Christ by the Holy Spirit. As a non-Jew I am forever grateful that God has extended his kingdom into our midst.
the archives near Emmaus 
Great point that the Abrahamic blessing is extended to us Geniles through the Gospel. NT Wright’s “Justification” was helpful to me in fleshing this out. In the Gospel, God is not only interested in reconciling individuals with Himself, but individuals with each other, and groups of people with other groups of people. Also adds an interesting light to “In Christ, there is neither Jew nor Greek, male nor female, slave nor free…”
@Chris,
Yes, ‘Justification’ is a great book. I read it as well. Sometimes with books like that you read it, then go back to the text, and you say “ah ha, I see what he is saying now”. I think this is one of those situations.