I’m currently learning this 
A Kettlebell is a centuries-old Russian training tool that looks like a bowling ball with a handle. The kettlebell appears in a 1704 Russian Dictionary (Cherkikh, 1994).
It appears that, originally, kettlebells were counter-weights used in Russian markets. Country folk started throwing them around and eventually they became very popular in Russia as a training tool. In 1913 the Russian magazine Hercules reported “Not a single sport develops our muscular strength and bodies as well as kettlebell athletics.” A Russian strong man was referred to as a kettlebell man –girevik. Girya is Russian for Kettlebell. Although kettlebells develop strength, a kettlebell-trained body is not bulky. quoted from – Sonomafit.com
Great, fun and effective workout! 
And to those who wants to learn and know how is this equipment used for workout, check this video from youtube My favourite is the turkish get up! ( but in the vid, it is only half turkish get up)
[youtube]ZWVnIwJD0Pg[/youtube]