maximillianos - 10:34 am on Jun 26, 2010 (gmt 0)
You cannot accurately determine where your site ranks any more due to personalized search. Even if you go through a new ip with no cookies or history of search, that does not even help since that does not portray the majority of users who do have a history of search on their machine.
My advice, don't look at where you rank in search as a measure of anything. It is counter productive and can misguide down a road where you waste time, money and resources making changes based on a stat that no longer is consistent or measureable.
Instead focus on your webmaster reports and your traffic logs.
Reading where you rank in serps is a dead science.
Now if you want to blame the layout changes, that too is out of our control. Googles can and does rotate what you see for any given search based on a number of factors including each machines history of search and location.
It is not what most SEO's want to hear, but it is my opinion that checking serps rank is a useless stat now a days. And this was done I believe by design by G. Which is actually a really good design, causing folks to focus more on what they can control, their own sites, and less on what they can't control.