The US Military has announced this year's deadlines for shipping to soldiers to ensure they arrive by Christmas Day. This applies to troops in Iraq, Afghanistan and other overseas deployments. As they instruct, it's important not to include the name of a foreign country in the address, since that will shift it out of Military Postal Service and into the even slower international mail system.
Parcel Post Mail: November 12th
Parcel Airlift Mail: December 1st
Priority Mail: December 4th
Express mail (may not be available to certain destinations): December 18th
Hanukkah is early this year--December 1st--so by these timings, your Hanukkah gifts should be postmarked by October 19 via Parcel Post Mail. Very soon.
For security reasons, the military no longer allows anonymous gifts to GIs (as my elementary school class sent during the Gulf War), but if you'd like to support military families, consider a donation to an Armed Services YMCA near you, or Operation Homefront.