Yeah I suppose iTTL would be nice. Have you seen any write up that details the difference between it
and the current TTL - matrix ?
The TTL that the S3 is planning on using is Nikon's now extinct D-TTL. Fuji and Kodak had very good flash metering being able to somehow use the sensor in the flash metering as the Nikon film SLR's do.
Nikon tried to be tricky, and made D-TTL a digital only feature that was compatable with DX only flashes (SB28DX, SB50DX, SB80DX, and the new SB800 - which is both DX and iTTL.) It used a quick preflash to meter, but didn't work consistantly well. Those that used it, learned it and were fine, but on days when you would least expect it - you had a headache fussing with your flash.
iTTL is apart of Nikon's new "Creative Lighting System." It was first implimented with the SB800 and D2h. And now in the D70, and upcoming SB600 (which is not backwards compatable with D-TTL like the SB800.) iTTL is a Godsend. Nikon really took back it's lead in flash technology with this. The flash metering is still based off a preflash, but they nailed it. The plus is that iTTL also TTL meters wirelessly with remote flashes. No more do I worry about blowing a wedding dress to do a flash exposure for the skin tones!
I own a D1x, D1h, D100, and D2h. The new iTTL on the D2h takes the cake - hands down. I've used the D70 with my SB800 and seen the same great iTTL results. If Fuji is dumb enough to add D-TTL to their lineup, they are investing in a system that Nikon has discontinued in favor of a better one. This will make flashes hard to come by outside of the SB800.