Where’s online advertising spend going? Over half of it is being placed on the top four Web portals (Google, Yahoo, MSN & AOL), according to a recent eMarketer report. That’s consistent or greater than the four previous years. Not only that, revenues on these portals continue to climb, even through the US economic downturn. eMarketer predicts Google’s online ad revenues will increase by 27% in the US in 2008.As you may already have guessed, Google’s share of those online revenues have nearly doubled to 57% in 2007 from 30% in 2004. No surprise, there; but now you can tell your boss the exact number and be a smartass!