Using ISBLANK and ISPICKVAL in Formula fileds of salesforce.com

ISBLANK(Close_Date__c) &&

(ISPICKVAL(Status__c , "Closed - Filled") ||

ISPICKVAL(Status__c , "Closed - Not Approved"))



- ISBLANK(Close_Date__c) returns True if the Close_Date__c is blank

- ISPICKVAL(Status__c , "Closed - Filled") returns True if the Value of the Status__c pick list is  Closed - Filled

- TEXT(Status__c) = “Closed - Filled” {Same as above}, returns True if the Value of the Status__c pick list is  Closed - Filled

- && means both values should be True then only True.

- || means either one of the value is True then only True.