Asus has issued
an official statement with regard to the warranty void sticker over the memory/expansion slot on the EeePC. The company has gone on record stating that if someone removes this sticker in a country where these types of stickers do not follow the laws of that country, the warranties will not be voided.
The statement can be found on Asus's U.S. Website. Apparently, the label will be replaced by a different label that, according to Asus, will "warn users that ASUS will not be responsible for the damage caused by improper hardware changes."
There has been quite a lot of confusion with regard to this sticker and the possibility of upgrading the RAM in the EeePC, but it seems like there's nothing to worry about if you've already done this. However, bear in mind that if you damage your EeePC in any way, Asus will not honor the warranty.
You can find the full statement here