BMA180 accelerometer. How does it manage to share pins between I2C and SPI?
I've seen exactly the behavior you're afraid of on an ADXL345, which uses the same I2C/SPI selection scheme.  I had another SPI device that used different clock polarity and it happened to emulate an I2C start code, the ADXL345 tried to talk out of turn as I2C.  Bad news.

I carefully rewrote the SPI as bit bang instead of using the peripheral, making sure to not change the MOSI line while the clock was high. (This is the I2C start condition.)  That seemed to solve things.

If I was starting from scratch, I would try to use I2C bus instead or a dedicated SPI port for the ADXL345.

Apparently I wan't the only one to encounter this.  This paragraph appeared in a later revision of the ADXL345 datasheet: