I need to script the creation of data in SharePoint, and part of this requires that I upload a slide library list template using PowerShell. Is this possible?
You can cheat using Webdav :
 according your comment, here is a way to find the correct url.
This worked for me, with a SP application having a custom AAM (yourspwebapp is not the hostname, but a virtual hostname). I checked locally... did you want to do this remotely ?
[Edit2] if installing Webdav is an issue on your server, you can use the following snippet :
Or you can use the sp OM, as Jimmarq suggests
WebDav might work for others, but I found a way to do it using the SharePoint object model. (I used the folders indicated by Steve B--thanks.)
I saw the template in the "Create" page, so everything seemed to work ok.