There is a "themes browser" you can use to insert stuff. I haven't found a explicit template that automatically uses transitions, etc, from the same theme, but if you select a given theme (like "Comic Book", "Documentary" and so on), those all pretty much match.
I messed around with some of them just now but was unable to quickly recreate some of the ones from iMovie.
But I'm quite slothful.
I'd imagine with some work between the Generators and Themes, something could be done.
edit:
I did some more surfing around the 'net and found this at Apple.
https://discussions.apple.com/message/15983209
It seems to imply that it *should* be possible to use iMovie to make the effects, and then import them into FCP X, but that's not happening, yet.
Digging through the imovie.app contents, all I can find is the sound files, as well. There are a bunch of video clips, but they're the sample clips used in browser.
