Thank you both for the answers!
The output redirection indeed works fine without the quotes, and more importantly, it also works on a script file:
wolframscript -o -f test.wl -format PNG > file.png
where the last line of the script file is a Print of whatever plot I want. That's pretty cool. Seems like it was really just a Windows issue.
Your CloudEvaluate-and-copy approach also works. However, I had some hope that there'd be a standalone wolframscript installer soon which would allow us to run code on machines that do not have a local WL kernel. (Maybe even with a portable executable that doesn't require admin access, that would be really awesome.) I'm not trying to skimp on the license, but it's just not always possible or practical.
David - that's a valid point about the cloud credentials, especially with the all-purpose Wolfram account (where the same credentials will get you into the user portal and this forum and all the other cloud services as well). Maybe a second dummy account would help, but I have a feeling that that's very much not encouraged... For what it's worth, the stored credentials on my computer look encoded at first glance.
Anyway, wolframscript is still awesome for use with a local kernel, I really apprectiate the addition. I like the frontend as much as the next person, but sometimes scripts are just so much more convenient.
