I found this:
From your Android phone, dial *#*#4636#*#* and then wait a couple of seconds. The testing menu will appear. To exit back to your normal phone, just press your back/exit button. If you're going to explore the various options on the testing menu, take care. Many of my friends and colleagues have tried this on their own phones, and no one has had a problem. But you never know.
As for the method to turn off data, select the first option on the testing menu (phone information), then press your menu key. You'll see a selection of buttons, one of which says "disable data connection". Press it, and you're all done. To re-enable your data connection, go to the same menu, where you'll find that the name of the button is now "enable data connection".
works OK on my new Defy+ (v2.3.4) I use it to prevent dataroaming costs!