It can synchronise with your iCal and Mail accounts. It will be more useful if it had an iPhone App. Something I will be checking out when I have a better look in the morning.
I also want to tell you about a Twitter service called TweetLater. I have been using the free version of that and finding it useful. I can set it to auto follow someone that follows me and even to unfollow someone that is an unfollower. I have set it to send out a welcome message to new followers also. The paid version does a fair bit more though.