They are for sure peered together through EZRI Inc. (Levin brothers own ISP). According to a traceroute, Imageshack seem to be the internet service provider of Powerset: 
 bonita:~ samuel$ traceroute powerset.com
 [...]
   7  tge1-3.fr4.sjc.llnw.net (69.28.171.66)  119.812 ms  114.540 ms  116.356 ms
   8  imageshack.ge3-1.fr4.sjc.llnw.net (208.111.152.106)  135.034 ms  135.472 ms  135.122 ms
   9  gi5-1.bas1.aa.powerset.com (208.76.46.165)  142.041 ms  139.165 ms  141.869 ms
  10  w2.aa.powerset.com (208.76.46.17)  135.569 ms  134.921 ms  135.400 ms
Search queries and user behavior on query result from Imageshack is extremely valuable data for Powerset.