The Output window actually has interesting information in it that is worth looking at when you're learning about ClickOnce. The first lines of output show a fairly standard Visual Studio "build" but after that, the ClickOnce publish starts:
------ Publish started: Project: AboutVBClickOnce, Configuration: Debug Any CPU ------
Connecting to 'http://localhost/AboutVBClickOnce/'...
Publishing files...
Verifying AboutVBClickOnce.application... (1 of 6)
Verifying AboutVBClickOnce_1_0_0_2.application... (2 of 6)
Verifying publish.htm... (3 of 6)
Verifying setup.exe... (4 of 6)
Verifying AboutVBClickOnce.exe.deploy... (5 of 6)
Verifying AboutVBClickOnce.exe.manifest... (6 of 6)
Publish success.
http://myserver/AboutVBClickOnce/publish.htm
========== Build: 1 succeeded or up-to-date, 0 failed, 0 skipped ==========
========== Publish: 1 succeeded, 0 failed, 0 skipped ==========