On the signup screen, I expect that clicking the "Terms of Service" link will open the terms of service (either in the app or in a browser window).
When I click the "Terms of Service" link, nothing happens.

This seems to be back. @rfaile313 and I can both repro after seeing a customer run across this issue in 2370416-zen.
EDIT: This was on Windows 10 with latest app version.
@belcherj can confirm, but I believe this fix isn't out yet. Version 1.8.0 was frozen before this issue was reported/fixed, and due to the GM we haven't had a release since then. It should be fixed in the next release.
Ahh, you're right:
https://github.com/Automattic/simplenote-electron/blob/v1.8.0/lib/auth/index.jsx#L149
Looks like the old version. I'll let the user know.