Unfortunately, the service requires that you are a customer with one of their current partner networks: Bright House Networks, Time Warner Cable, and Verizon FiOS TV. If you are an Internet-only customer with Verizon FiOS, you only have access to ESPN3. Curling, anyone? ESPN does note, however, that they will be gradually adding supported TV providers.
The current version of the app isn't optimized for the iPad, but a tablet-specific version is expected in May. WatchESPN is also expected on other operating systems, but they've provided no specific timeline.
If we were forced to guess, we'd say the Android version is arriving in May along with the iPad version. Is anyone else surprised that they didn't debut this before March Madness?
source: iTunes via Redmond Pie