Indeed.

UBIFS requires Linux kernel 2.6.22 though because it uses UBI which was included in that .22. They also tested it on OLPC, but first on N810. At least that was the case begin of april (interesting post by developer). It cannot be used on N800 because its designed for flash without FTL. We don't know what later versions will of N-series + Linux bring, but if people want N900 with 2 SD cards and no real flash w/o FTL, UBIFS is not useful. Because the WiFi driver is now open source, later versions than 2.6.21 can be used for N810 sooner or later. This opens doors for HE, and perhaps indeed UBIFS.

http://www.linux-mtd.infradead.org/doc/ubifs.html good page with intro for UBIFS.