You don't know Glenn. He's a natural story teller and while proud of what he's done, he recognizes that he's just one of many people trying to create something that hasn't been created before. In reading into his comments of his history with Steve, you're viewing him as intentionally pumping up his own story. The truth is he's trying very hard to be honest with the listener as to his comings and goings with Apple and with Steve.
He worked with him closely, then stepped away and came back. Multiple times. By telling the story of this, he lets readers know that he wasn't always by his side and that he left to try other things but circled back at different junctures in his life and in Steve's.
Knowing Glenn and his successes and failures and talking with him over many a margarita at Compadres (after long bouts of writing NeXTSTEP code with him), the story brought strong memories and a very clear voice of different periods and circumstances across several years. He shows an arc of ups and downs in both careers and a lot of hard work and sweat that often didn't get notice until many years later if at all.
Rereading the story, I don't get boastful at all. I get much appreciation for being able to be on a pretty cool ride and being able to create some great products. There's also disappointment in some hard work that didn't pay off. But above all appreciation for someone who continually rolled up his sleeves to get in the ring, take chances, and build something... or in this case tell a damn good story.
Work on the stuff that shows things visually before you work on other behind the scenes parts. Try to get it to show it doing a number of things asynchronously. (A screen that populates a number of actions or data points is going to win out over a single action step-by-step demo.)
Have a screen or two that's nicely designed and laid out. Good graphics, buttons, icons.
Work on your presentation. Many hackathons are beauty contests where a tight presentation and good look will win out over serious stuff under the hood. Have a simple imaginative funny description of what it does. (Funny apps tend to win out over more serious apps.)
Build an app that can get the audience involved. "Everyone take out your cell phone and text ..." "Go to this link and sign in with your twitter credentials." "Take a picture of the person next to your and send it via email to this address."
Do something that makes use of existing data or data that can easily be gathered from users when they sign up.
It's abstracting above having to manage and think about servers. Just as most developers stopped having to think about registers or print drivers or low-level network protocols or memory pages. You still have all these but you gain big by having technologies that let you abstract away from these levels of detail. Buzzwordy, yeah sure. But the meaning and implications are pretty powerful.