WhatsApp for Android is all set to arrive on tablets. But it is said to be arrive only in Beta. As of now WhatsApp was not available on Android tablets. However, now WhatsApp seems to be working on the same.
You can now download WhatsApp for tablets from Google Play Store but only if you tend to be a beta tester. It is seen to offer a limited number of features and functionalities since it is still in beta. Through the development process more features will be added.
For this purpose, you will be requiring a tablet which has a SIM slot. Also you need to have a second WhatsApp account since the beta app will not allow you to pair the tablet with your smartphone and to use the same account on both the devices.