I've noticed some interesting results when checking keyword rankings for clients as of late. Sometimes I find their sites ranking in a set position, yet my client often sees the same phrase ranking in a different position. This appears to be happening on more and more of a regular basis. I understand the possibility of hitting different data centers, but there is something more going on here.

Sometimes when I search I may be logged in with a gmail or yahoo account. At times this has resulted in different rankings being displayed. I check rankings for various keywords for my clients on a fairly regular basis. Does this mean that the results returned to me are personalized (as I am frequently using the same query)?

I would like to pose a few questions to all SEO's out there:

• Has behavioural targeting begun?
• To take it one step further, what is the effect of hosting a domain in Canada vs. the US for example?
• How much of an affect is geo/demo/behavioural targeting having on rankings at this point?
• Does the search history of an individual affect future results?

I've posted a few of these questions at webmaster's world. I'd like to here from everyone on this. Feel free to add comments to this post.