OpenSlowaris ZFS NAS?
Whilst it might sound good, the reality is it would be trapped between two existing markets. On the low end we have a plethora of Linux-based NAS devices, from single disk home-NAS to multi-disk SOHO products all with embedded Linux on ARM or similar chips, and all available at a cheap price. As well as serving up NAS, many of these devices are plug-and-play and also add value by providing embedded print servers (and with a much larger range of print drivers than Slowaris). Their makers can take advantage of the open nature of real Linux, whereas if they go with Slowaris then they have all the fun of a pretend-open license and the possibility of NetApp slapping a lawsuit on them if they use ZFS. Until OpenSlowaris adopts a real open licence and the WAFL courtcase is resolved I can't see much use in the low end.
If you look higher up the chain then you meet a large array (pun unintended) or commercial multi-disk NAS devices which come from reputable companies with established channels and sound support services. Here Slowaris and ZFS do stand a chance as licencing costs can be hidden away in support charges. Problem here is there is already not just a host of Linux-based devices, but cheap Windows Storage Server offerings whch don't require the Slowaris skills most SOHOs don't have. At this level the majority of offerings have simple, polished point-and-click GUIs. And again, NetApp is keen to protect their ownership of the commercial NAS market and will more than likely clobber any vendor going to market with a product with ZFS. Probably the only chance for a real, commercial NAS is Oracle badging the current Sun storage kit, as Oracle may have the will to go toe-to-toe with NetApp, but that also makes it less likely for another vendor to pick it up as they then have to compete with Oracle.
The problems for ZFS are not largely technical, more legal. Until the purchase of Sun goes through, Larry can't make a real move on clearing up the ZFS/WAFL courtcase. Until the purchase goes through, the courtcase is likely to remain stalled. And with a fair few people lining up in attempts to block the purchase (Sun shareholders as well as rival companies), it looks like the whole deal may get spun out for a while longer. By the time it all gets cleared up - if it all goes Larry's way - it may be several years down the road, and by then tools like BTRFS will have gained market and mind share.
Slowaris and ZFS will work for the hobbyist community, especially the Sunshienrs, but that won't make it a commercial success.