It still has a button.
If you are one of the person who just bought the latest Apple iPad 2 and are having trouble enabling Airtel’s 3G service, you might want to follow the following steps.
Before this, you need to enable 3G service on your Airtel SIM. If you’ve already activated 3G service, go ahead with the following steps below; if not, text “3G” to 121 to activate 3G service on your Airtel SIM.
Now follow the steps and check out the screenshots:
1) Go to “Settings” from your iPad 2 Home Screen
2) Go to “Cellular Data” on the “Settings” pan on the left (as shown in the snapshot below)

3) Keep the “Cellular Data” On (tap on it to toggle On/Off)
4) Now go to APN settings (step 3 in the snapshot above)