That hotfix will correct the security issue where users with full mailbox access would be given send as rights by default.
Didn't realize earlier, but you can apply the permission to the OU that you want (like I originally stated, but took back for some reason). In the advanced security permissions change it to apply to "user accounts" and you will have send as in the list. No hotfix installation necessary. However, note that this behavious will change in Exchange 2003 SP3.
http://www.good.com/faq/17540.html