1. Deploy Twitter plugin downloaded from Marketplace (either CE or EE)
2. Go to My Public Pages
3. Add the Twitter portlet to a public page (I tested this in the User Profile page as well)
4. Configure it to show tweets from Liferay (or another public Twitter profile)
5. Add the Activities portlet
Twitter feed appears in the Activities portlet.
Twitter feed doesn't show up.
Liferay 6.2 GA6 + 6.2 Twitter App
Liferay 6.2.10 GA1 + 6.2 Twitter App