My second GTX 570 arrived today!
The first results on 3dmark vantage and 3dmark 11:

Click image for larger version.  Name: vantage sli2.jpg  Views: 876  Size: 269.5 KB  ID: 118519

Click image for larger version.  Name: 3dmark11 sli.jpg  Views: 857  Size: 320.7 KB  ID: 118520

I think it's good for a start!