So, Matt Cutts has got the whole SEO community all fired up about a long and detailed post in which he explains why some sites have seen fewer pages indexed since the BigDaddy update.
Basically, people have reported fewer pages on their sites being indexed, and have (of course) written to Google to complain and demand an explanation. Matt Cutts has now come out and said exactly what some people are doing wrong:
“The sites that fit “no pages in Bigdaddy” criteria were sites where our algorithms had very low trust in the inlinks or the outlinks of that site. Examples that might cause that include excessive reciprocal links, linking to spammy neighborhoods on the web, or link buying/selling.”
Please note that he's not just talking about buying and selling links – excessive reciprocal links are bad, too. However, he gives some examples of sites that are guilty of this, and they all seem to be linking to completely unrelated sites. Real estate sites linking to Omega 3 fish oil or hair care sites, for example. In other words, if you've got a few reciprocal links to other software sites, I don't think there's a reason to panic – as long as we're not talking hundreds, anyway.
Matt also writes that sites with few incoming links should expect to see less of their pages indexed, which is interesting.