Old World of Work
A Blackberry Fool was a traditional English desert made with blackberries, cream and sugar. A delight.
New World of Work
A Blackberry Fool is a person who feels that through the constant (once every 4 minutes or less) checking of their Blackberry they will (1) make their world a better place (2) keep e-mail at bay (3) seem more important. Of course they are wrong on every count. A pain.
You may also like Blackberry Picking.