That's just one of its features. SD deinterlacing should be what the chip does better than other players. How well the other NR and "detail enchancment" features work remains to be seen. 1080i->1080p is only really necessary for 1080i content - HD broadcasts or HiDef discs mastered in 1080i - and you have a 1080p display with 1080p input capabilities. With SD, if you need 1080p, 480p->1080p would be the way to go. It's possible to go 480i->1080i according to Dale Adams, but deinterlacing is usually done first. The 1080i->1080p isn't fluff because it lets SO sell into the stb, external processor, and even the display markets also with the same chip. If the chip performs well, you wouldn't need 1080p output from a source device if this chip was in a 1080p display (and is capable of going in displays). 480i for SD and 1080i for HD.
Opportunity is missed by most people because it is dressed in overalls and looks like work. -- Thomas Alva Edison