Nope. It is a single client to single server. iFolder and Dropbox are multi-client to single server. Meaning I can synchronize a folder between my desktop, my laptop, my workstation, and access them via the server's web UI if I'm ever on some other machine.
It explicitly tells you to avoid the use of csync for laptops and desktops. I believe that's because it has very poor offline mode support -- it expects the machines to be connected at all times. (Could be wrong, didn't read much past where it said not to use for laptops.)
"doesn't "requires kernel-level support on the client machine" either."
Yes, actually, it does if you want it to be automatic. I have far better things to do with my life than open a shell and type in a command or three every time I update my resume in Abiword or tweak some financial data in Gnumeric. When I save the file, I expect it to sync automatically. That requires some kind of daemon running using something like inotify so that it can automatically detect the changes and sync for me. Likewise, if I have my laptop and desktop running at the same time and I change a file on my desktop, I would like to see it updated on the laptop without me needing to go tell the laptop explicitly to update.
Unlike DSCM, I don't generally require versioning of said files, though I won't mind if it's there. Dropbox does versioning automatically for example, though I've never needed the functionality.
DSCM's don't really solve the same problems though. They focus on managing a tree of data organized by commit and history. That is massive overkill when all you need is synchronization (even with versioning). It's also a poor fit, because the concept of a "commit" is really out of place here. CVS's per-file commits are actually more appropriate in this case if any SCM is relevant. But on top of all that, the DSCM's don't support the best protocols for these sorts of things. They're optimized for syncing text files (source code mostly) and put a lot of effort into diff calculation and the like which is largely useless for binary files or even most XML file formats. Tools like iFolder additionally take extra care to avoid pounding the hard disk (no DSCM tries to throttle its disk access, for obvious reasons) and to avoid saturating your network connection (which, again, no DSCM does).
"Can't iFolder just scan once at server connection, then passively monitor & propagate immediately via inotify/gamin/fam"
That is precisely what it does, same as the Dropbox client. There are limits to what inotify can handle so it may need to still poll in some cases. That is largely what gamin does for you -- inotify when it can and polling when it can't.
To sum up, one tool does not fit all needs. DSCMs are great for source control. They are not great for general purpose file synchronization. Likewise, iFolder would suck as an SCM. Use the right tool for the job instead of trying to make one tool (even a generally versatile one) fit every single possible slightly related job under the sun.