Attach vCard is a script that can attach your vCard to all outgoing messages, or to outgoing messages just from accounts which you specify. It thus provides a workaround for Entourage's lack of an "Add vCard to signature" feature. New in X: You no longer need to make the vCard yourself: the script creates it and updates it on each run.
What's new in Attach vCard
Version 1.1 fixes a bug in the PREFS script that didn't carry out changes to select specific account(s), and is implemented in Unicode and so will work for any user name in any language.