Currently it is possible to add someone from another organisation to projects under the 'My work' tab at the community profiles. This may be desirable in some cases, however I myself was added to projects which I didn't collaborate on. I didn't know this untill I just randomly checked this recently. For this reason it would be great if you would receive a notification whenever your community profile is added to a project.
Ideally, you would also want to be able to accept or decline that you are being added to another project.
Good idea Jordy! As we're currently redesigning the community profile, we will definitely add this feature.