No way is she 5'8!!
There is no way that Jessica is 5'8. Here she is with Kate Beckinsale (who is listed as 5'7) and wearing the same height heels and she is obviously shorter:
http://gofugyourself.com/fug-or-fab-jessica-biel-with-bonus-nicely-played-kate-beckinsale-07-2012
Also, at the Stand up to Cancer benefit, there is pic of her and Gwyneth (who is listed as 5'9), and Jessica is at least 3-4 inches shorter. I think JB is more like 5'5 or 5'6 at the most.