Are we approaching an economic slowdown?
analysts are predicting so.

If that is the case, the economic slowdown will dampen consumer spending and thus advertising.

Already in late 2006 Yahoo started warning about its advertising revenues slowdown.
delays with Project Panama.
first to suffer a decline in advertising in the previous Internet cycle, although back then most of the blame could be tracked back to the over-reliance on dotcom advertisers.

PS: This is Post III of my 2007 outlook post series