Why is google notebook a bad idea? That's how I got to this subject.
I'll try to be brief, at first...
CVS is the first form of controlling versioning system that I know of. Although I've never used it myself, I know it's old, and there's the "new" SVN, which is also outdated nowadays. I've tried using bazaar, and it seems nice, but smoething is still missing there. Dropbox, which I'm happily using across windows and linux, does have a CVS alike system, but I haven't really tried it. It's really promising, because it's the first one I've seem that can handle online and offline quite well. Why? Because it's simple and uses a lot of simple built-in technologies that new tools such as google notebook choose to ignore and forget that exist. Things like a user's file system and local storage (the first purpose of hard drive). Computers nowadays don't need HD if they're connected to the internet. But it's still really usefull to have your own offline box from time to time.
Wikipedia, by far, is the best online CVS i've seem. It's about perfect. But it's missing the offline part, and every issue that comes along with syncing those. rsync seems like a great tool to help with syncing issues but it lacks a decent GUI. And that's a big down. JFileSync does most of the job, although not as powerfull as rsync, it's portable. Supposedly. I can't make it work flawless on linux.
Well... With all that, I'm trying to find a solution where all that is merged, and working. Not a merged tool, I hate Microsoft for insisting on doing that kind of thing. A merged solution. It's something that can integrate many tools or not. That depends on the needs, and on what's already done, with solid background and/or functionality. Well designed tools which were sucessfully applied without trying to be a freaking swiss-knife-army, such as Microsoft Word or even Windows. Or even google notebook.
By the way, I've loved notebook for quite a while for its usefulness and simplicity, but after some considerations, it's google turning same wrong sideway ms did a while ago.