Here's the official Word from the TSA website:

Raised Threat Levels:

The U.S. threat level is raised to High, or Orange, for all commercial aviation operating in the United States, including international flights. Flights from the United States to the United Kingdom are also Orange.The U.S. threat level is raised to Severe, or Red, for all commercial flights flying from the United Kingdom to the United States.

The U.S. threat level is raised to High, or Orange, for all commercial aviation operating in the United States, including international flights. Flights from the United States to the United Kingdom are also Orange.

Increased Aviation Screening Procedures:

The Transportation Security Administration (TSA) is implementing a series of security measures, some visible and some not visible, to ensure the security of the traveling public and the nation's transportation system.

TSA is immediately implementing the following changes to airport screening procedures:

NO LIQUIDS OR GELS OF ANY KIND WILL BE PERMITTED IN CARRY-ON BAGGAGE.

SUCH ITEMS MUST BE IN CHECKED BAGGAGE. This includes all beverages, shampoo, suntan lotion, creams, tooth paste, hair gel, and other items of similar consistency.

Exceptions: Baby formula and medicines, which must be presented for inspection at the checkpoint.

Beverages purchased in the boarding area, beyond the checkpoint, must be consumed before boarding because they will not be permitted onboard the aircraft.

Passengers traveling from the United Kingdom to the United States will be subject to a more extensive screening process.

These measures will be constantly evaluated and updated as circumstances warrant.

How every passenger can assist in security:

    * Pack lightly, without clutter, to facilitate easier screening.
    * Arrive earlier than usual at the airport.
    * Cooperate with TSA personnel at checkpoints and with airline personnel at all gates.
    * Be attentive and vigilant to any suspicious activity and report it to authorities.

Increased Border Protection Procedures:

U.S. Customs and Border Protection will increase enforcement efforts in international arrival areas including the use of advanced targeting tools, special response teams including baggage and aircraft search teams, baggage x-ray equipment, specially-trained canine units, and explosive detection technology.

DHS has also mandated that all flights from the United Kingdom transmit passenger manifest information for intensive screening prior to departure from the gate. In addition, passengers on these flights and all other international flights will be subject to heightened inspection upon arrival in the United States.

Apparently it's no carry-on bags AT ALL in the UK.