I guess that you use a pinoccio when Wifi is not the best, for example considering that its consumption is far higher than with a pinoccio. Also, the most important is "where is the bottleneck". If you have a serial link between the OV7670 and the microcontroller, it would not be that useful to send the image through Wifi, since the bottleneck is the serial link.
Storing the image on a SD card for buffering is not a very good idea because the power consumption of SD cards is high. For buffering, it is better to use a SRAM chip with an SPI interface. However, if you have a high compression ratio (and a small size image like 320x240), the available RAM of the pinoccio might be enough (depending on what is used by the rest of the application).