Making Active Directory changes atomic

If you go into Active Directory Sites and Services, you can force replications. Open the Server object and click on the NTDS Settings. This will give you a list of their replication partners for GC data as well as regular DC-DC traffic. As I understand it, you can force replication by going to each of the connections, right-clicking on it, and choosing "Replicate Now".
_{(source: sysadmin1138.net)}

There is an even easier change. Just reset the users password. That is one of the few instant replications that AD performs. No need to run site replication

EDIT:

Small edit. It's not completely instant. What is does is forward the change in an out-of-band update. (It doesn't wait for normal replication cycles)

however, it's probably about as close to instant that you can get with AD.

Make the change to one domain controller. Then open up AD Sites and Services. Then drill down to each site, Servers, DC, NTDS Settings, then right-click each connection and choose Replicate Now.

Note: Each connection will tell you the From Server and To Server for the replication.

Note: Obviously, start the first replication From the DC you made the change on.

If you have a small domain, this shouldn't be too taxing a task. If you have a larger domain (more DCs) then you could script this.

To script, you need to use the CMD command called REPADMIN. For a full description of the command type REPADMIN /?. In short, you would use the command in a way similar to this:

REPADMIN /replicate DC1.yourdomain.loc DC2.yourdomain.loc dc=yourdomain,dc=loc /u:yourdomain\your_domain_admin_account

To find out the replication partnerships for a specific DC from the command line type the following:

REPADMIN /showrepl DC1.yourdomain.loc

Once you have figured out the right path/order to replicate to all your DCs, you can just dump all the commands into a batch file, and execute it when you need to replicate changes out quickly.