Why do a stand up?
Last week I had a call from the lead that is not on same site as the QA ask "can we do a deploy, or will this affect the testing?". It's nice to be asked, and the answer was easy "In the stand up the QA said she was not testing in that environment today..." and just to keep everyone chatting "...give her a call though".
Why demonstrate at the end of the iteration?
Business availability on my current project is not a problem, they're at stand up, they're around the team, they're on the phone, they're there, it's great. Despite this proximity and their close involvement with work as it progresses, at the last demonstration they asked "what are we doing about saving in this app?". Then there was a discussion about what they understood the behaviour should be and why. It was great to have this feedback with entire team there to hear, question and understand their ideas.