I don't know if they're available yet as a frame only. They shoudl be later this spring, though. There are like 5-6 guys on my race team that are riding the new Hei Hei in various build combinations (and one on a near stock Hei Hei Supreme) and the lightest that I know if is in the 22.0-22.5 lb range.
His build is something like this, I think:
Stock Hei Hei 20" frame
2007 Mavic SLR wheelset
Maxxis Crossmark tires (probably w/ Stans kit)
rim brakes (I don't know what calipers) with Avid speed dial levers
stock SID race fork,
full X.9 drivetrain,
2007 Ritchey WCS stem/bars,
Thomson Elite seatpost,
Truvativ Stylo Team (?) cranks,
........etc, etc.
I'm not sure how much else can be shaved of that bike. Unless you started going crazy with ti hardware, etc. It's pretty much top shelf stuff across the board.
Note, his modified Hei Hei is lighter than the other guy's 18-19" stock Hei Hei Supreme.