Price Ceilings - a great example from China and Xinhua Press' China View (this is the daily website):

Everyday since I returned from Xishuang Banna, there have been long lines of trucks waiting for diesel outside the petrol stations.  Our travels have been much longer due to the time required to try and navigate the roads around the lines of trucks.  The news reports soon explained - in the official newspapers - the issues. 

PetroChina suffers a refining loss from Xinhua Press (the official Chinese press) - (note that CNPC is called PetroChina):

"The break-even point of our refining business was at about $66 to $67 a barrel of crude for each dollar gain beyond that level, we will lose 3.24 billion yuan in a full year," he said.

The company has also asked the government to cut fuel import tariffs.

PetroChina's refining business saw a loss of 20.68 billion yuan in 2007, representing a reduced loss of 8.48 billion yuan compared with the previous year.

.....

PetroChina is the country's second largest refiner. The biggest refiner, Sinopec, said yesterday it will receive 12.3 billion yuan in government subsidies to ward off oil processing losses.

CNPC, as of this post (3/29/08), had not yet received word about their request for a subsidy (or I haven't seen it).  So PetroChina called for an increase in prices of gasoline and diesel.

As gas shortages spread, will they or won't they increase prices next month, there is considerable uncertainty.