Define dependencies on PS modules/scripts hosted on PowershellGallery.com (or similar source) in script modules and templates.
Allow defined dependencies on powershell modules or scripts (and versions) from a nuget compatible source such as PowershellGallery.com. Allow these dependency definitions anywhere powershell is used in Octopus. Tentacle should install the scripts/modules into the Powershell Session prior to performing any release steps.
This would allow for more complex powershell modules to be made available for Octopus to use, as well as a means for keeping the PS code up to date outside of Octopus.
Bishoy Demian commented
This sounds like a great idea. I would add caching of those modules and only downloading/installing them when the first time the dependant step is executed.
Also controlling which version (SemVer) of those modules to pull would be a plus.