To get you started, we’ve worked with the engineers from the Calendar and Docs teams on two highly requested features: a simple way to see your Google Calendar agenda and get an alert when you have a meeting, and a gadget that shows a list of your recently accessed Google Docs and lets you search across all of your documents right from within Gmail.
This is definitely a great news, since it will save a lot of time for people who use Google Calendar, Google Docs and Gmail quite frequently, to activate the integration with these services, go to Settings > Labs and enable the services.
Once you have enabled the new labs features you will see your Google docs account and Google Calendar account integrated into Gmail sidebar.
This is a definite exciting feature and will really come in more than handy to many people, in addition to the above two features they have also added support to add any gadget to your Gmail account by pasting the URL of its XML file.
So what does the introduction of custom gadgets mean? One thing is for sure, would be no need for add-ons to integrate external services into Gmail, for eg the Remember the Milk add-on for Firefox, and you can directly load the RTM gadget into Gmail.
Pretty exciting right, what do you think about it?