One of the great things on Google Apps is that Google is constantly examining ways to improve their products. Every week since the beginnings of Google apps, they have changed and improve everything they offer. There are no sudden shocks just gentle updates which you get instantly. Gmail and Google Calendar are only two applications that made a huge difference in my business. If you want to know more about the new and old features of Gmail and Google Calendar, including recent updates, read it.
Working with teams is very easy with Gmail and Google Calendar. For a startup, there is the instant messaging service where you can easily swing you between the chat, vocal video and group chat. All are accessible in a browser, so no need to change.
If you want to see how you have interacted with a certain person, the 'people widget' (which was released this year), allows you to see all communications and shared documents to that person.
When it comes to organizing a meeting time being internal or conference, you can use intelligent reformulation that can be found in Google Calendar Labs. This year, a new feature called "Appointment Slots" has simplified the planning of the meeting. You can configure blocks of times you want to offer as appointments.