Small but highly publicized strikes by Walmart retail and warehouse workers last autumn 'set the labor movement abuzz and gained new respect for organizing methods once regarded sceptically' reports Labor Notes. US trade unions are deploying new, flexible tactics including the use of 'open source organising' to create economic leverage with hostile employers:
http://www.labornotes.org/2013/01/walmart-and-fast-food-unions-scaling-strike-first-strategy