Hello,

Does anyone know if there is any birthday reminder plugin for kopete?
If no, is there a way to request this feature to be developed?

Thank you.

You may wish to look into KDE Telepathy at this point, as it is much more active in terms of development.
I can confirm that KDE itself does not ship with a Birthday reminder plugin for Kopete, although one could possibly exist on kde-apps.org.

Could you elaborate on what you want to happen when it's someone's birthday?

I don't see how this ties into the instant messaging client.