I've managed to redeploy zimlets but did see a couple of issues that I'd like to share:
1) Once a zimlet is deployed, you cannot undeploy and then redeploy it (they should be symmetrical operations, right?).
Code:
$ zmzimletctl deploy com_my_zimlet.zip
INFO: Installing ...
$ zmzimletctl undeploy com_my_zimlet
INFO: Uninstalling...
INFO: Removing ...
$ tomcat restart
...
$ zmzimletctl deploy com_my_zimlet.zip
...
Error: cannot update Zimlet config for com_my_zimlet : system failure: unable to modify attrs
To re-deploy, I had to re-grant the acl, then enable the zimlet, and finally re-deploy it.
2) zmzimletctl uninstall isn't listed in the zmzimletctl help.
On to some development for me!