How to show DateTime in Visualforce page in User's Time Zone instead of GMT in Salesforce?

Sample Code:

1. <apex:page StandardController="Opportunity">  
2.   
3.     GMT:   
4.     <apex:outputText value=" {0,date,M/d/yyy h:mm a}">  
5.         <apex:param value="{!Opportunity.LastModifiedDate}"/>  
6.     </apex:outputText>  
7.     <br/>  
8.     User Time Zone:   
9.     <apex:outputField value="{!Opportunity.LastModifiedDate}"/>  
10.       
11. </apex:page>  

Output:

For using apex:outputText tag use

1. <apex:page>  
2.       
3.     <table>  
4.         <tr>  
5.             <td><apex:outputText value="User Local Time Zone time is: {! NOW() }" /></td>  
6.         </tr>  
7.         <tr>  
8.             <td><apex:outputText value="GMT Time Zone time is: {0,date,yyyy.MM.dd G 'at' HH:mm:ss z}"><apex:param value="{! NOW() }" /></apex:outputText></td>  
9.         </tr>  
10.     </table>  
11.   
12. </apex:page>  

Note:
<apex:outputText value="{!NOW()}" />  - it will show GMT time.
<apex:outputText value=" {!NOW()}" /> - it will show time in your local time zone (note that blank space has been added before the left brace).