Basic capabilities of numerous key social media websites. Some data is opinion-based, but I'm continuing research and will update as possible.

1. Business
Input Response Collation Share To For Events Mobile Apps
Culture
iOS , Android,
Text, image, video, Follow, comment, like,
Facebook Lists Twitter Event pages, check-in Blackberry, Nokia, Facebook
poll, check-in repost
Windows Phone
iOS, Android,
Expected (esp. BlackBerry
Tweet, mention, DM, LinkedIn) for
Twitter Tweet, mention, DM Hashtags, lists Facebook, API Hashtags, accounts (unofficial), SMS, Twitter
follow, retweet marketing, job Windows Phone,
listings, GoogleTV
recommendatio
Text, image, video, Like (“+1”), repost, ns, etc
Google+ Contact circles none Event pages iOS, Android Google+
event, link follow
Comment, like,
Text, link, message, iOS, BlackBerry, Palm
LinkedIn recommend, message, Contacts list Event pages LinkedIn
job ads Pre
follow company
iOS, Android,
Follow, comment, like, Growing, but
Foursquare Check-in, text, photo none Check-in BlackBerry, Windows Foursquare
‘to do’, lists still suspect
Phone
Likes, reposts, Tags, separate Facebook,
Text, image, quote, Twitter Growing, but
Tumblr comment w/ repost, blogs, tracked Tumblr
link, chat, audio, video still suspect Pre, during (less),
ask questions search
post event
Image only w/ caption Likes, reposts, change Boards, Expected if iOS, Android
Pinterest Pinterest
& link description, comments hashtags relevant
Instagram Image w/ caption Hashtags Growing Hashtags Instagram
Follow, comment, like
Storify Import to boards Storyboards Expected Info collation Storify
Documents,
Follow profiles, Facebook, Use hashtags
Slideshare slideshows, video w/ Tags Very high Browser only Slideshare
comment, favourite LinkedIn Post-event share
caption
YouTube / Embed, YouTube /
Like/dislike, favourite, Pre, during, post
Vimeo / Video w/ caption Tags, playlists Facebook, Expected iOS, Android Vimeo /
playlist event
Ustream Twitter, G+ Ustream
Created by Nicole Jensen - nicolejensen.com Data correct in Australia as of Friday, 31 August 2012
This Social Web Basics Table is free & licensed under Creative Commons License, Attribution 3.0.