Theoretically*, if you have vino - empathy can share your desktop to another empathy client by transparenty proxying vnc via xmpp.
* - I’m using tp-gable from git and currently it’s in a quite a bad shape - namely doesn’t support TLS1.2 so I was unable to test and prove it actually works.
Yes, I read some about Jitsi and still have it on my list of very interesting things. Will try to use it to get into personal contact with an au-pair we are looking for ;-).
Looked for further information about desktop sharing and found:
It’s possible to share your desktop so others can view it, but it’s not possible for others to interact with your desktop
Information is from the link below which describes that it is not just that easy to get that feature to work (which does not make it less interesting).