First bit of feedback is about the Loading text after sign-up : "Reticulating splines.." while it's cool and makes me smile inside I do believe it might not cause the same effect to the majority of the population. If your goal is to scale beyond HN you might consider making it as non-threatening as possible to the lay-man
Any suggestion for replacement?
Another suggestion is to ask people if they want notifications to threads they've replied in. It's ok for this to be false by default. HN doesn't have this.. the argument I've heard is that people want it this way in order to not be "wired in" to HN because they feel they spend enough time already but not even having the option is not great IMO, especially in your case.
You want to give people the option to be wired in to your platform, that's the fastest way it will grow. If you want to be ethical you can make it as easy as pie to turn off notifications for a post. Not sure if you can do this straight in the notification or not but at least when they follow the notification you can give them a corner screen pop-up or something to disable notifications for this post if they've set the default settings to always get notified
Maybe just making the “…” dance to indicate that it’s loading would remove any doubt that the page is doing something for those users that might not understand it. I personally love apps that have some charisma!
It has been awhile since I played SimCity 2000! (great game)