Rumor: Google Limiting Site Exclusions

AdWords advertisers to be encouraged to exclude by category

The debut of the broader Site & Category Exclusion tool will
mean capping individual site exclusions to 5,000 per campaign.

Probably not many advertisers have more than 5,000 sites tagged
as ones where they do not want their AdWords advertising to
appear. Those that do, or want to, will have to abide by a
per-campaign cap.

Barry Schwartz at SERoundtable caught wind of the change via
comments made at WebmasterWorld. For advertisers with campaigns
over the cap, they won't be able to add any new sites until
they get below the 5,000 limit.