Bicycle Tutor

First post!
I have inherited a bike from a friend and it has a few problems. Most of them are easily fixable but one has me stumped.
The pedals are loose. Not the actual pedals themselves but the whole assembly that attaches the pedals to the bike. I can grab one pedal and give it a jiggle and the whole thing, pedals, gears, etc. will move about an 1/8 of an inch. What is the fix for this??

Probably a loose bottom bracket which is the bearing assembly that holds the pedls, crank arms, and chainrings.
Look at these tutorials:
http://bicycletutor.com/part/bottom-bracket/
You might just need the final adjustment to take out the play.