The general format is
{!$ObjectType.<<object>>.<<field>>.<<property>>}
Display the plural text of an object
{!$ObjectType.Task.LabelPlural}
Display the 1st part of an object records id
{!$ObjectType.Task.KeyPrefix}
Display the length of a field
{!$ObjectType.Task.Fields.Await_Call_Back_Time__c.Length}
Display the help text of a field
{!$ObjectType.Task.Fields.Await_Call_Back_Time__c.InlineHelpText}
Display the data type of a field
{!$ObjectType.Task.Fields.Await_Call_Back_Time__c.Type}
Display the label of a field
{!$ObjectType.Task.Fields.Await_Call_Back_Time__c.Label}
Also for field sets
http://www.salesforce.com/us/developer/docs/pages/Content/pages_dynamic_vf_field_sets.htm
