Talked to a couple of other people and they see the same thing. Can anyone else confirm the same, or did we somehow get picked out from millions of accounts to have a down traffic day across a few different markets?
@scout - don't knock the arbitrageurs, some of my best traffic comes from such sites on Yahoo. I accept not all such partners are perfect, but those driving traffic from MSN and/or Adwords are often better in terms of conversion than the majority of premium partners out there - on any network.
I'd far rather have my traffic from such sources than for example community based sites, or those content sites designed specifically to display a million and one Adsense ads - if that's not a bad user experience Google, I don't know what is (not that they care, because unlike arbitrage, these sites add to their bottom-line and not someone elses)!