I applied the facilitated naturalization (I qualified for this since I've been married to a Swiss for at least 3 years and have been in Switzerland for a total of 5 years, with the last 12 months actually in Switzerland ) to Bern ( Federal Office for Migration FOM) at the end of July 2008. Received a letter in September indicating that my application was accepted and it may take about 12 to 24 months depends on the local work loads (cantonal/communal). Then I received an invitation letter to an interview in the local police station (in fact they were ready to do it on the phone, but I preferred to visit them). It was as short as 15 minutes friendly talk mostly on what I have been doing since I moved to CH, my wife’s and my personal info (such as birthdates, places, home and work address...). It was in November. Then about 2 months after, at the end of December, I received a letter asking my wife and me to sign that we have a true marriage and not planning to separate soon. They also requested a copy our marriage certificate and my declaration about no criminal history. 1 month after I sent the requested document, in February, I received a letter from Bern indicting that they approved my naturalization and asked me to pay 750 CHF, however, I have to wait for about 2 months to receive the final decision (it is a legal period in case of any opposition could raised by the origin canton or commune). In fact, I receive the final approval confirmation letter from Bern in the 5th week... The entire procedure took about 10 months for me.
The final confirmation letter is enough to apply for the passport (takes about 4 days to get it) or the ID (takes about 3 weeks), if you live in the same canton where you are registered (become a Swiss). If you live in a different canton than where you are registered (your Swiss wife/husband origin), you need to have an updated family carnet (where your new Swiss nationality is shown) for the passport/ID application.
I am ready to answer if you have any question. I wish you all whom are in this process...
Kraft