I'm a web designer/web developer and I can't find any documentation on KHTML's proprietary -khtml properties. I'm trying to add CSS3 to the next version of my site to show off some of the things that browsers are capable of however KHTML seems to be the least documented rendering engine. Any help would be greatly appreciated.

A grep of kdelibs/khtml/css reveals the following text, which can be found here http://pastebin.ca/1721938

That doesn't reveals what KHTML expects from them, but should give you a point to start from.

Unfortunately it seems that KHTML only has border-radius in regards to anything worthwhile from CSS3, property related that is; based of course only on that list.

I don't suppose there is a way to determine what version of Konqueror border-radius was introduced? I'm trying to detect browsers and their versions via DOM sniffing.

Unfortunately there isn't any way I know of, you may wish to try asking in #kfm.