Needless to say, I was quite disappointed when I came to find out that Zend_Pdf doesn't currently have any type of text layout support except for the exact position to place it. I created a small extension to Zend_Pdf, and building off of an idea from FPDF, I created Zend_Pdf_Cell.
His code is not officially included into the Framework, but has been posted for anyone to use if they might need it. It includes features like: the ability to create a cell and put text inside, position a cell, specify the height/width and format it with different fonts.
He also includes installation instructions (copy the file over, basically) and usage examples to get you started.