Just think on cars like my Xray T2's, sure I have to add weight now but later when the rules are changed, I just remove that weight.
Brushless escs will get smaller, maybe 10 ~ 15g less in a year or two less
I'll just swap out my servo for a shortie style or karbonite gears, 10 ~ 15 grams less
That micro RX will may shave another gram or two less.
Going to a Novak Light motor saves me another 17g
So i just found 50g to save on the electronics side to help with that lighter LiPO pack.
So just guessing, but dropping the Min weight by 100g in 2009 shouldn't be that extreme. If you want to make min weight and don't have the cash for uber tiny electronics, well go with a smaller LiPO pack like a 3200mah. That is the beauty of LiPO...it is scaleable!