If you use minted instead of listings, the latest minted 2.0 (probably not yet on tex-live) latex package does line wrapping in the source code blocks very elegantly.
(setq org-latex-listings 'minted)
(setq org-latex-minted-options
'(("linenos")
("numbersep" "5pt")
("frame" "none") ; box frame is created by the mdframed package
("framesep" "2mm")
;; ("fontfamily" "zi4") ; required only when using pdflatex
; instead of xelatex
;; minted 2.0 specific features
("breaklines") ; line wrapping within code blocks
))