The reason this is relevant in the discussion is that when you type in the url in chrome (arguably the top browser) the word in the domain and subdomain count as search words that show up in trends. So when you type "plus" for the g+ url it's added to trends. You can check that little fact by looking at the trends for "plus".
http://www.google.com/trends/viz?q=romney,+facebook&grap...
red=fb, blue= romney
The reason this is relevant in the discussion is that when you type in the url in chrome (arguably the top browser) the word in the domain and subdomain count as search words that show up in trends. So when you type "plus" for the g+ url it's added to trends. You can check that little fact by looking at the trends for "plus".