I tried Imovie 09, and in my opinion, it is still unusable for someone with an AVCHD camcorder. And it is really sad because I like how Imovie is easy to use, and all Imovies features.
I put a lot of hope in this 09, but I will need to wait for 10.
problems:
-Create archive feature, which seems promising, here is how it works:
You can create a complete image of your avchd files and folder structure, but, you can't make a partial image. It means if you forgot to delete the videos in your camcorder from your previous archive creation, your new archive will contain both old imports and new import. And there is no possibility of manipulating the content of the archive.
-You can't delete the imported files after having made your movie, or you lost the link between your movies and the imported files. Once you delete the imported files (which are quite huge compare to the original avchd files, so you can't keep online all your videos), the video thumbnails completely disappear from imovie, and you are left with your avchd archive you cannot view anymore unless you re-import the whole thing.
And last problem, which might just be a bug: after having made my movie using my imported avchd files, the maximum resolution available for export is 960x600. no HD export. (I did a full HD import)
I hope these points to be fixed in the next release to make avchd really usable, avchd camcorder is now the standard, and a mac should help people to easily make movies with an avchd camcorder.
Today, editing avchd movie is easier on a PC with sony vegas studio.