Deploying zimlets on zd2 is easier, but it is still a manual step. We are working on installing zimlets via UI - hopefully it will make to the final release of zd2.
Here is how:
1) Copy your zimlet bundle (should be a zip file) under the "zimlets" folder in "user data home". This link tells you where to find user data location on different platforms: Zimbra Desktop 2 FAQ - Zimbra :: Wiki
2) Shutdown ZD backend service: Zimbra Desktop 2 FAQ - Zimbra :: Wiki
3) Start ZD. The new zimlet(s) will be deployed during startup. And new zimlets will also survive future upgrades of ZD.