Alex Hornung has updated tcplay in DragonFly to 2.0, and cryptdisks is updated to match. If you have a short memory, tcplay(8) is the tool on DragonFly to manage TrueCrypt volumes. Is DragonFly the only BSD to have this? I think so, based on very few seconds of googling.
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Yes, DragonflyBSD is the only BSD to have this. With a Bit of emulation you can read external TC Disks on FreeBSD, but afaik Dfly is the only Unix that allowes to encrypt the local filesystem in that manner. TC itself only supports this feature on Windows.