BOSS v1 appears to be fine, at a guess it looks like the appid being used by the web.search table is not valid.

Correct Salathe, the default appid that YQL had provided is now disabled as part of the BOSS v1 -> v2 migration. If you provide your own appid to the query it should continue to operate normally however using the default YQL appid (i.e. not specifying any appid at all) will be blocked. Sorry for the trouble. We will be updating our table to require appid in the near future.