OK, finally figured it out. I was using the Digilent PMODBB which was causing cross-talk between the SCLK and MISO channel. Once I routed straight to the Zedboard PMOD header the problem went away. The PMODBB didn't give me any trouble with the ADXL345, so I don't get why I got it here.
The expected return for PROD_ID (32256) was 0100 0000 0110 1000 (16488). That '1' in the second bit was being driven low by the SCLK which threw the whole rest of the message off (this explains the resemblance in shape).
Anyways, thanks for the help everyone.