Bacon is pork which has been 'cured' (i.e. preserved) by immersion in brine (i.e. in salt water). So it's hardly surprising that it's salty! ;-) http://www.3men.com/bacon_making.htm
As the link says, they also inject the meat with salt water and phosphates to 'speed up the [wet] curing process'. This also adds weight, so you're paying for that salt water.