Watson in your pocket or a UI on your phone to a Watson in the cloud? Given the number of servers they used for the Jeopardy Watson I'm sure it's more like the latter.
For Jeopardy, they had to beat 2 champions in 3 seconds on a wide range of subjects. For a more specific topic or "good enough" answers, you would not need so much hardware. For example, they kept the whole database in 16TB of RAM!
