From the comments to an earlier post:
To answer in reverse order...
Contact groups at Oak Grove function similarly to cell groups: that is smaller groups within the church who meet together and learn, teach support each other etc etc More info here
The band at OG, is a contact group in it's own right, both for practical and spiritual reasons. We meet every week for music practice, but we share and pray and talk too. Then, once a month we leave the instruments to one side and spend time learning, reflecting and most importantly sharing communion with each other.
It's our regular time to check in with God and each other.
Does that answer your questions?
Out of interest, how do you do think over at Vineyard?