martinibuster - 10:17 pm on Apr 17, 2010 (gmt 0)
1) completely disregard these links to your site?
Your assumption that Google disregards reciprocal links is mistaken. That is an SEO myth.
2) dampen the weight they place on these links?
Another SEO myth.
3) treat them the same as any non-reciprocal link?
Google will treat them the same as any other link. Reciprocity only tells the search engines there is a relationship of possible relevance between the two sites.
Would you risk penalties of some sort if a large portion of your links were of this type?
There is no certainty either way, so you'll only receive opinions. But it certainly would stand out because it's unusual.
Non-reciprocal "reciprocal" links
Reciprocal is reciprocal, including three-way arrangements.