When you update the product regularly, and you also have Release Notes on your website, it makes it looks like it's growing and alive.
We try to release new features every month, and announce that to our community, but sometimes you need to focus on something bigger that will take months of coding. Then it's a good idea to create sneak peeks of it, share it with people, update them on the progress or even start an open beta (this is what we actually did this week :D)