In 2012 Switzerland had only partial coverage by Bing aerial imagery (see coverage map). This improved in the following years, however there are still large quality and age differences.
Swiss wide imagery is available from SwissTopo however a complete set of images would cost roughly CHF 60’000 without any guarantees that the data could actually be used for OSM purposes. A number of cantons have however produced their own imagery which in some case is available on more favorable terms. These are nearly always more current and of better quality, for example the imagery for the Canton Zürich is available with a nominal resolution of 10cm per pixel, The available imagery is either proxied by SOSM, for example for use in iD, or hosted directly. Even though we have good contacts with the cantonal GIS offices, we are grateful for pointers to new or updated imagery sources.
Further numerous cities have given us access to imagery and data: Berne, Uster, the City of Zürich. The canton Vaud has been very supportive with imagery and data for numerous smaller areas.