Matt Cutts has become equivalent to God on these things LOL
http://www.google.com/search?sourcei...link+exchanges
http://www.google.com/search?sourcei...tts+paid+links
The post about paid links
http://www.mattcutts.com/blog/how-to-report-paid-links/
has caused a stir.
Perhaps the other thing is since the Big Daddy update it appears that reciprocal link exchanges don't hold as much weight, as sites that had previously done well via such exchanges have lost ranking.
Again, it's all complete speculation, up to the individual to decide whether to take it seriously or not.