Planet13 - 6:47 pm on Jun 21, 2011 (gmt 0)

But on the other side, there are no positive ranking effects either ...

I wouldn't agree with that 100% - It might be dependent upon the keywords / niche one is competing in.

For the two-word keyword phrase that I track closely, several in the top ten appear to do quite well based primarily on reciprocal links.

Granted, it is not a particularly high volume keyword phrase, which might have a lot to do with it.

I think the only way is to look at the top ten results in the SERPs and go in and examine every link to those sites.

Now, having said that, I should also mention that the improvement in the SERPs for my pages that I have seen has been from primarily getting one-way links from authority sites. Those types of links still seem to be very valuable.