Jesus, his family, and his disciples are guests at a wedding in Cana. Somehow Mary, Jesus' mother, becomes aware of a shortage of wine and feels that she needs to make Jesus aware of the matter. This in itself is interesting because it suggests that Mary believes Jesus can do something about it. John tells us that this is Jesus' first public miracle but it seems that Mary is already privately aware of what Jesus can do. However, Jesus seems put off by his own mother's faith in him. He responds as if the shortage is wine is not his concern. Nevertheless, Mary persists in her faith telling the servants to do whatever Jesus tells them. In this exchange, Mary and Jesus seem to relate to each other as any thing but mother and son. Instead, Mary's interaction with Jesus sounds more like that of a disciple.
The other oddity of this story is the amount of space John uses to describe the jars which will contain the water which Jesus turns into wine. John gives us all kinds of descriptive details concerning these jars that might otherwise seem completely irrelevant to the rest of the story; they are stone, there are six of them, they are used for Jewish purification rituals, and they each contain twenty or thirty gallons. However, these details cause our minds to linger on these jars as we hear the story John tells. It is not only significant that Jesus turns water into wine. It is significant that Jesus uses these jars to do so.
I think John is using both of these oddities to point us toward the same truth; that our relationship to Jesus as Lord takes precedence over our usual relationships and rituals. Mary seems to know, even at this early stage in John's Gospel, that she can not relate to her son as any other mother would. She comes to him less with a mother's request and more with a disciple's faith. Even the incredibly important mother-son relationship must submit to the Lordship of Christ. Similarly, John also subordinates concerns of ritual purity to Christ. The water jars that John mentions were used for an important cleansing ritual; to use them for anything else would have likely been an offense to Torah observant Jews. However, it is these jars that Jesus has filled with water that he will turn to wine. Jesus' first miracle sets aside important Jewish laws of ritual purity so that he can provide more wine to keep the party going.
Jesus overturns our typical way of doing things, our normal way of relating to each other and to God. But in doing so, he is making possible the great wedding feast to which we have all been invited.