I just read an answer to another question, in which Roger Attrill wrote:
You might not need to say Thank you if this is a very frequent action or if your user's won't appreciate the nicety - just say Scheduling report...!
I'm reminded of the following passage from About Face 3:
Nass and Reeves suggest that software should be polite, but the authors prefer the term considerate. Although politeness could be construed as a matter of protocol—saying please and thank you, but doing little else helpful—being truly considerate means putting the needs of others first. Considerate software has the goals and needs of its users as its primary concern beyond its basic functions.
Does expressing thankfulness make the interface more friendly, or is it presumptuous for a subordinate machine to suppose its master has any interest in its own well being?
Should software ever say "thank you"?