Ask Slashdot: Free/Open Deduplication?

ltjohhed writes: "We've been using deduplication products, for backup purposes, at my company for a couple of years now (DataDomain, NetApp etc). Although they've fully satisfied the customer needs in terms of functionality, they don't come across cheap — whatever the brand.
So we went looking for some free dedup. software. OpenSolaris, using ZFS dedup, was there first that came to mind, but OpenSolaris' future doesn't look all that bright. Another possibility might be utilizing LessFS, if it's fully ready.
What are the slashdotters favourite dedup flavour?
Is there any free dedup software out there that is ready customer deployment?"