What is the vineyard? Isaiah uses it to describe the house of Israel in 5:1-2. Who are the husbandmen? They likely refer to at least the Jewish leaders of Israel, but if the house of Israel is actually supposed to be Gods promised relationship with humanity, then the husbandmen could refer to the Jews in their entirety they have mishandled and mismanaged their status as the chosen people of God.
Who are the servants which the owner keeps sending? They are the prophets whom God regularly sent to Israel who, like the servants here, continually went unheeded and were persecuted (at least by those in charge).
Finally the owner sends his son (Jesus) whom the husbandmen kill because they are jealous of his power and potential a foretelling of Jesus crucifixion that would have been obvious to Marks audience. The sons identification as Jesus is made clear because the language of beloved son is exactly the same used in the first chapter when a voice from heaven announces at Jesus baptism Thou art my beloved Son, in whom I am well pleased. This also answers the earlier question as to the source of Jesus authority: Jesus comes to the vineyard with the authority invested in him by his father, God.
The parallel breaks down somewhat, though, because the story Jesus tells suggests that if the original servants had been treated well, then the beloved son would never have been sent; but is this a notion that any Christian today would seriously accept? Unlikely it would entail claiming that Jesus only came to save people because the Jews were so wicked. This is, however, a natural reading of Jesus parable.
There is also a potential problem in the fact that the parable describes the son being murdered by the tenants, but Jesus is executed by the Romans arent they effectively the others to whom the garden is to be turned over? On the other hand, its likely that early Christians would have seen this as another confirmation that Jesus was really killed by wicked Jews, thus furthering the development of Christian anti-Semitism.
Historians report that leasing land to tenant farmers was common in Judaea at the time and, in fact, it was also common for these farmers to feel oppressed by absentee landlords who demanded crushingly unreasonable fees. This would have allowed Marks audience to identify with the situation, but from the wrong way around: they would have more likely identified with oppressed farmers (who represent wicked Jews) rather than the absentee landlord (who represents a righteous God).
The owner's reaction to the murder of his son is understandable: he destroys the wicked husbandmen and turns the vineyard over to others. This is a reference to the destruction of the Temple by the Romans and the expulsion of the Jews from Jerusalem.
Thus, this parable is a sign to Marks audience that they are meant by God to take control of the vineyard the inheritance of Jesus as being the chosen of God. This is yet another gospel passage that has seen a lot of use by Christians who have attacked Jews and Judaism because it depicts Jesus as asserting that God has judged Israel and found it guilty.