UPDATE: It’s dead! 🙁 The mobile site works though. Unless this is patched, the mobile site is the only recourse we’ll have on webOS phones for YouTube access. The TouchPad can of course still view the full website. Some users are reporting it still works for them so it appears to be regional as the shutdown implementation goes into effect.
The Verge reports that Google is to kill off older YouTube Apps at the end of April. This will affect webOS users, unfortunately.