i dont think so if it changes the width of website or any other aspect then only pagerank could come into play
If you're talking about a keyword theme, yes. Having unique titles while maintaining an overall cohesive keyword theme will help your rankings. If you're talking about a design theme, no. In other words, no.
Oh, really? Well, then, you should let Wikipedia know about that, cause they seem to be ignoring that rule. Bastards are ranking for everything under the sun. Bastards have top rankings for [karma sutra], [evolution of man], and [abraham lincoln]... guess they didn't get the single themed memo rule that Google sent out, huh. You're making an incorrect causal relationship correlation really, although I can see why people still think that way. Often times in competitive markets it is the companies most focused on a particular theme that are going to spend the most money on seo'ing that themes keywords, so therefore you see single themed websites at the top of the harder to rank for phrases much of the time. They aren't ranking better due to only having one theme though. There really is no "single theme bonus" per se. In the end, Google still ranks pages, and not sites. -Michael