RED ALERT: I hope you aren't flying today

For the first time ever, the nation's airlines have had their alert status set to RED. This is in response to a terror plot uncovered by British authorities.

Homeland Security took immediate steps that included barring passengers from carrying liquids, including beverages, hair gels and lotions, on planes. It said travelers in both countries should expect long delays.
A British police source said the plot was believed to involve a "liquid chemical" device.
"Over the last few hours, British authorities have arrested a significant number of extremists engaged in a substantial plot to destroy multiple passenger aircraft flying from the United Kingdom to the United States," the statement released by the DHS press office said.

So, (1) if you do not have to fly today or this week, don't! and (2) do not buy a bottle of water to drink on the plane. The only liquids allowed as carry-ons will be baby formula and prescription medicines, and even those will likely be heavily scrutinized (read: you will be locked in a small room while it is chemically evaluated).