I installed Quick Settings and turn off my mobile internet with this app. I have a motorola milestone with 2.1
However, that causes some trouble sometimes. When disabling it I lose more often my wifi connection. Android seems to try switching to APN when going to sleep. Turning on APN also does take a lot of time occasionally. Worst thing happened to me a few months ago: I had my APN turned off through Quick Settings. This app got an update and all of a sudden I couldn't connect to the internet over APN anymore. I had to do a full reset of my Android because of that.
Can you suggest a way to turn off APN in a less harmful way? (I still wonder why Android doesn't include that.)