You can download it from here
Exchange 2010 SP2 is a complete installation software pack, so for new Exchange installations, you can use it to start with from scratch.
Also when you use it for updating your current installations, be aware that you need Schema- and/or Organisaiton Administrator rights, because it contains a Schema update for your Active Directory.
And this Schema update needs to be execute in the domain where the Schema Master Role exist. So run setup /prepareAD not in the domain where you operate your Exchange Servers, it will not work. You need to go to the root domain, if there is the Schema Master or you have to move the Schema Master on to a domain controller in the domain where you operate your Exchange environment.
And remember that you should wait for replication across your AD after you’ve performed the Exchange 2010 SP2 Schema update.
During you’re waiting for replication, you can use the time to install the ‘IIS 6 WMI Compatibility’ feature. It is mandatory for your following Exchange 2010 SP2 installation, because of the new ‘Outlook Mini’ feature, which requires this feature on your CAS server roles.
5 minutes for /prepareAD
15 minutes for replication (more if you have higher replication times set on your site links)
5 minutes for feature prerequisits
30 minutes for finishing SP2 setup per system
so you should be through with it within a hour for your first system and schedule 30 minutes for every following systems …
Reboot after SP2 installation should not be necessary.
And think about to disable Anti Virus Scanning on the box you’re going to perform Exchange 2010 SP2 Setup for upgrade.
Read the prerequisits before starting your installation