I just noticed that you receive ingame messages when you complete a building or unit. A text message 'Unit complete' or 'Building complete' appears. I haven't seen this in any other video so maybe it's an option which you can switch on and off? Source: http://www.youtube.com/watch?v=PkcP_dBzTJg
Actually, this has been a feature of Brood War/Starcraft since it was released. For instance, the adjuntant in Brood War announces 'Add on Complete' when a particular building extension has been completely built.
Yes but that was a vocal announcement, I can't remember there being text messages that you can read on screen saying a building or unit has completed. I'll check my SC copy tonight to see whether I'm awfully wrong.
Uhmm...if you turn off sound, I believe you get the text announcement. that's the only time, I believe. I personally like that SCII did it this way, though.