He speaks - we listen. Tantek Celik's post "Pandora's Box (Model) of CSS Hacks And Other Good Intentions" is definitely a must read post for anyone who is developing with CSS these days. Many interesting notes on the background of various hacks - which I found very useful in gaining a broader context of the hack/filter - plus some sage (common sense) advice at the end.
Note: it was also posted at webstandards.org.