UIView *topview = [[[UIView alloc] initWithFrame:CGRectMake(0,-480,320,480)] autorelease];
topview.backgroundColor = [UIColor colorWithRed:226.0/255.0 green:231.0/255.0 blue:238.0/255.0 alpha:1];

[self.tableView addSubview:topview];

from http://stackoverflow.com/questions/1166236/light-gray-background-in-bounce-area-of-a-uitableview

iPhone: Change the background color of the bounce area above a UITableView

Objective C