Came across this topic that talked about Kuler being ripped off from ColourLovers.com
I am not being biased with any group but i think both the interfaces do not match each other and their interactions are totally different.

I  first started out with Abobe Kuler, got the hang of creating themes sooner than ColourLovers.com
ColourLover.com seemed more community based with lot of things happening, which i really didnt have time to check out.

I just needed to create combinations and deploy them on my design at work and the time factor matters!!
Whenever i have some time or a break, i go back to re-edit the name and tags at Kuler.

I agree with the differences (comments) stated by Josh Chernoff on Chad Udell ‘s site that:

1. colourlovers is more community based. forums and blogging and a better commenting rating system
2. Kuler is more technical and logical. Provides CMYK, LAB and RGB with color theories and a over all a better color wheel).
3. Kuler is more API friendly with a great deal of redevelopment emphasis.
4. The web technologies are different. Kulers was in a way to provides a better understanding of Action Script’s capabilities as kuler surfaced just about the same time AS3 was introduced.