Allow me, as a Tube Train Driver to give you a bit of info on it.
The strikers are all Metronet workers, these are the people that maintain the trains in the Depots, and the Rails the trains run on when carrying passengers.
The drivers are not on strike, but in the interests of safety of the passengers, we have refused to take an unprepared train, onto an uninspected track.
This is why there are no trains on the affected lines.
Main reason for the strike.
Regardless of whats being put out, there are two main issues,
As you must know, Metronet has folded, although the wrkers are still getting paid, I believe, by London Underground, but since Metronet has folded, no money has been put into the workers pensions, and they want the lost money reinstated.
The other reason, is that Ken Livingstone, promised, without consultation with London Underground, that the workers would be taken back 'inhouse', to London Underground. this, LU have refused to do.
Hope that explains a bit about it.