According to Bruce Clay SEO's should be shaking in their boots in response to Google developing a sixth sense. In a great article Bruce shares his thoughts on Google's attempts at nailing intent based search.
Although I can see the sense in developing this technology I think it's going to be tricky to get it right, although if anyone can Google can. In trying to understand a users intent, based on their historical activities for example, Google runs the risk of becoming, well, irritating.
It's like the e-commerce thing where you get told 'hey! users who bought that also bought this!!'. So fucking what I just want this!! I normally think....
Don't get me wrong, if Google can get this right then it could be a great thing and will restore users confidence in the net. More than once I've heard people berating Google results as annoying and irrelevant.
Many think it's creepy when computers try to understand a real person, others will find it helpful. As for the SEO's, well if you are following SEO best practice I don't really think you've got anything to fear from personalised search.