Saving apps to memory card

I was told with the 2.2 update we would be able to save apps to our memory card. I have had it for almost a month now and haven't been able to find a way to do so. Any one have any ideas?
When it tells me I am low on system memory space and to delete apps it pulls a screen that when you go into the app has a greyed out option for move to sd card. I have tried every app and I can't move any of them.