How to make contentplaceholder read only?

We can make content place holder in Master Page Read only by putting ControlMode="Display"

<SharePointWebControls:DateTimeField FieldName="RenewalDate" runat="server" id="DateTimeField1" ControlMode="Display">

Difference between siteCollection.AllWebs and siteCollection.OpenWeb

siteCollection.AllWebs: Returns all the webs within site collection,It is a sharepoint property. for example If you wish to inherit same master page in all subsite in site collection, you can use this property.

siteCollection.OpenWeb: It is method and take SPWeb as parameter. It used to access particular web within site collection.

SharePoint 2010 Feature

Today I come across about wonderfull site on SharePoint 2010. Have a look when have time
http://officesharepointpro.com/Articles/tabid/149/nodeid/1982/The-Curtain-Rises-(Just-a-Bit)-on-SharePoint-2010.aspx