I think that there should be a "world" lens that integrates all network-based searches. Could be web searches, wikipedia searches, contacts, etc. The home tab should be about ... home. It should only integrate local stuff. (Beyond of making ubuntu get blamed of becoming adware*, it is a serious usability issue to mix local and network searches).
*After reading Mark's statements. Sorry, but this definitely turns ubuntu into adware. Users will be receiving unrequested shopping suggestions when possibly looking for stuff in their own systems and it does give Canonical a profit. The only name for this is that they are ads.
If the default was to turn them off so users wanting to see suggestions would be able to turn it on. Then they would be a useful service. But enabled without request they are ads. The best solution for now would be not making these results appear in home tab unless the user sets an option to make them.
Otherwise 12.10 is going to be very grim for ubuntu's reputation. It is a shame because unity was getting so much better now, but if it is estigmatized with ubuntu's adware attempts, it will really be the killing blow on its chances of adoption.