Validating deployments

The 3 main avenues for deploying changes in Salesforce.com - change set, Eclipse IDE, and command-line/batch/script with Ant - all provide an easy option for validating your deployment before they actually get applied.  You can address any potential deployment issues before they happen in the actual run, which is great.  In fact I try to always do that so I'm fully prepared for a successful deployment.  As a reference, the validation option in the 3 tools is as follows:

Ant tool
Add a checkOnly attribute to the deploy action in your build.xml.

<target name="validation">
       <sf:deploy username="..." password="..." serverurl="login.salesforce.com" deployRoot="staging" checkOnly="true" maxPoll="180" /> 

</target>   

Eclipse
Use the Validate Deployment button.


Change Set
Use the Validate button for the inbound change sets