Several times already we (Microsoft) infomred about a change we will ahve to make in the way we handle ActiveX. On February, 28 we published a Security Advisory to pre-warn about this change: http://www.microsoft.com/technet/security/advisory/912945.mspx.
Finally we infomred that we will include this change in the next Cumulative Security Update for Internet Explorer. As you may expect, the next Security Update cannot be far away.
Therefore I would really like you to test your applications that use ActiveX in order to make sure that you are able to roll this update out