WPF Databinding thread safety?

Value changes fired by INotifyPropertyChanged are automatically marshalled back onto the dispatcher. (http://blog.lab49.com/archives/1166)

Fire this event on any thread you like...

Value changes fired by INotifyCollectionChanged are NOT reliably marshalled onto the dispatcher. (http://csharplive.wordpress.com/2008/09/11/wpf-data-binding-observablecollection-cross-thread-binding-support/)

If you need to update an observable collection from a different thread, follow the advice in this link

In addition to @Rob Fonseca-Ensor's answer, there is some good news for those lucky enough to use WPF4.5:

WPF enables you to access and modify data collections on threads other than the one that created the collection. This enables you to use a background thread to receive data from an external source, such as a database, and display the data on the UI thread. By using another thread to modify the collection, your user interface remains responsive to user interaction. (https://msdn.microsoft.com/en-us/library/bb613588(v=vs.110).aspx#xthread_access)

There's a helpful summary by Jonathan Antoine: http://www.jonathanantoine.com/2011/09/24/wpf-4-5-part-7-accessing-collections-on-non-ui-threads/