Receptional_Andy - 9:09 pm on Jul 9, 2008 (gmt 0)

the mechanism that is related to site links does have an effect on the serps

Personally, I would rephrase that to "the mechanism that is related to the serps does have an effect on site links" based on the effects you've reported. Serps create sitelinks, sitelinks don't create serps. Of course, there's an element of 'feedback', in that Google can look at how people utilise sitelinks, and so the relationship is not entirely that simple.