I can confirm it works, But You have to put html AND plist on dropbox. It works also for non-enterprise OTA, i.e. You want to share app with your dev. team.
I did:
a) on my site I made a page with this link:
.. href="https://dl.dropboxusercontent.com/u//(your DB id)/ipa.html">MyApp
b) on DropBox I wrote another HTML page:
.. https://dl.dropboxusercontent.com/u/(your DB id)/MyApp.plist"> Tap to Install MyApp
c) moved plist on DropBox but leaving it to POINT to my old server (no https)