It depends on the size of the update. From my experience in social gaming and consumer web, we use tooltips and login modals greetings for most changes. For mor

It depends on the size of the update. From my experience in social gaming and consumer web, we use tooltips and login modals greetings for most changes. For more significant ones, we use blog posts (kind of like doing a press release) and then email all users to let them know. As long as you have a unsubscribe link, you're not going to be considered a spammer especially if they signed up for your service. The benefit of engaging with users (increasing conversions and building community) outweighs the cost of annoying your fringe users (churn). This is an interesting experiment on emailing users. http://searchengineland.com/extreme-email-experiment-how-much-is-too-much-60755 http://searchengineland.com/extreme-email-experiment-how-muc...