Are you sure? Have you tried an actual query?
balajin@4r6s1:~$ curl -o /dev/null -s -D - "http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20html%20where%20url%3D'http%3A%2F%2Fwww.yahoo.com'&diagnostics=true"
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Cache-Control: no-cache
Content-Type: text/xml;charset=utf-8
Vary: Accept-Encoding
Date: Wed, 04 May 2011 12:05:49 GMT
Server: YTS/1.19.8
Age: 0
Transfer-Encoding: chunked
Connection: keep-alive
I see that www.downforeveryoneorjustme.com seems to be truncating all the arguments to the website and query.yahooapis.com with no arguments give an error, which makes the site thinks that it is down.
Please cross check
-balaji