The Swiss pegged their currency for the last several years to the Euro, at a set exchange rate.
To maintain that peg, they have had to buy euros, to keep the value of the franc from rising. With the EU about to announce a MASSIVE QE, it will devalue the Euro even more.
The Swiss decided to no longer play the game, because they would be forced to buy tons of Euros (by printing tons of francs) to maintain the Franc’s value.
Your recap is nearly identical to the story on today’s frontpage of the WSJ. Where you differ is the impact the “small” Swiss banks will pay. According to WSJ, the smaller Swiss banks wanted to avoid the effects of QE scheduled for next week.