Yes, but I limited it to color scheme.
I have three themes which correlate to three subdomain sites, each on a distinct topic. Within topic A you get color A, in the content and in the forum. Image buttons are also keyed to the theme.
My forum then has the three color themes displayed together on the index page, and sets you up to expect what color you'll land in should you click a forum link. It's divided so that it looks like stripes of color horizontally on the page.
I'm working on a new front page that is a portal which collates summaries from the sites and the forum areas. It looks like stripes of the same colors running vertically.
So I was shooting for consistency all the while I varied the colors to reflect the content. Navigation works the same and URL structure and layout is at least 90% consistent across my subdomains. For a bonus they all tie back to your forum login and greet you when you arrive if you're a cookied forum user (Hello linear, you have 11 messages). And I set different ad display policies for cookied forum users as well.
Overall, I'm judging it as indifferent. I like it, no one's complained yet, and my wife thought it looked good. I'm not sure how else to judge it. My old look was achromatic (#ccc page backgrounds), so the color is quite a change compared to that. My community is nascent at best, so perhaps it's premature to decide on effectiveness in my case.