For those holding out for a region 1 NTSC edition of The Last Mistress, it will be coming out on November 18th from Mongrel Media in Canada. There's no definitive word on the extras yet, but it will apparently be uncut, and English subtitle options are confirmed.
There's still been no announcement of a US DVD release date; but now... who cares? ;)
Update 12/18/08: According to this review at exclaim.ca, this DVD has "no extras to speak of," so you're definitely best off with the region 2 disc at this point. That's possibly just as well, since this version seems to be a bit hard to find...
By the way, Asia Argento is amazing in this. She's really grown as an actress since her early roles.