Here's a link that says:

If you're buying an I Bond for a gift and you don't have the Social Security Number of the person you're buying the bond for, simply use your number. Even though your number will be printed on the bond, you'll incur no tax liability, and it won't count towards your annual purchase limit. Social Security Number is used for tracking purposes only, such as in cases where the savings bond is lost, stolen, or destroyed.

http://www.savingsbonds.gov/sav/sbigift.htm

and using the annual purchase limit link in this site you'll see:

I Bonds purchased as gifts using your own Social Security Number (because you didn't know the recipient's) won't count towards your annual purchase limit; however, they will count towards the annual purchase limit of the gift recipient.

[This message has been edited by sk3 (edited 06-28-2002).]