Yes, I have seen these in Spain, but I am not sure that they're obsolete. They were used on a circuit supplying heaters. I think they may have a very high rating for heavy appliances that need >16A. Although, that plug seems to be rated 16A/250V...
They may also be Spain's alternative connector used for special purposes e.g. the way BS546 round pin connectors are used in the UK.
I notice the socket's fused too. Could it have been a Spanish implementation of ring circuits using fused socket outlets rather than fused plugs?
Like in the UK and Ireland there may also have been an effort to get rid of 2 pin configurations that allowed grounded plugs to be mated with ungrounded round pin outlets by introducing a new totally incompatable system.
Perhaps it was tried and abandoned as schuko became the defacto standard across Europe. Even the italian system is going that way.
[This message has been edited by djk (edited 01-20-2006).]