If you are about to install Exchange 2010, one of the checks in your checklist should be Update Rollup 1 for Exchange 2010. This would come after you have installed Exchange 2010 on your server. But what if I tell you that you can slipstream RU1 with your Exchange setup?
All you have to do is populate a folder with RU installer and use /UpdatesDir switch with setup.com. The example would be setup.com /role:mailbox /UpdatesDir:”C:\ExchangeSources\RUs”. Once this command successfully completes, you will see that the exchange install is complete and your determined patches from the UpdatesDir are applied to the server in single step! Isn’t that a thing of beauty?
Exchange Server Update Rollups are cumulative so you don’t need to have RU1 installer if you build a new server with RU2 in future. All you need is RU2 installer file in UpdatesDir and exchange source to install from.
There are many other useful switches to automate Exchange 2010 setup. you can find the reference on Technet.