Yes this proposal to cover some of the GBR with shade cloth has actually made national news (article below) in Australia and is commented on at Federal CABINET level.
We are saying that if the GBR is suffering from GW, then surely this must be revealed in the long term temperature data from Willis Island, 400 kms plus east of Cairns. Clearly Willis island has experienced no warming trend in 67 years.

still being talked about 20 August 2012 –
Shade cloth could be used to protect coral reefs, scientists say

Friday, November 3, 2006. 11:05am (AEDT) ABC Online News
Results of reef shade cloth trial proving positive

Researchers involved in a trial of shade cloth to protect the Great Barrier Reef say the early results are encouraging.

Federal Tourism Minister Fran Bailey says the Commonwealth is considering funding the use of shade cloths to protect vulnerable parts of the reef from global warming.

Marine biologist Russell Hore from Reef Biosearch and Quicksilver Connections in Port Douglas says the shade cloths block out heat and light and reduce the damaging effects of global warming to coral.

He says while the idea seemed laughable at first, everything should be considered to protect the reef from future bleaching.

“We haven’t had the full effects that some places around the world have had, but it’s really just a matter of time and if we don’t start to seriously look at this issue then we certainly could be looking at large areas of coral reefs around the world dying off,” he said.

Mr Hore says four five-metre square shade cloths have been tested over the past two years.

“I don’t think we would ever consider shading the whole reef, logistically that would be an impossible thing to do, but what we are trying to prove at the moment is the fact that if you can reduce two of the major factors that cause coral bleaching, one of them being light intensity, one of them being temperature, that you can help to reduce the levels of coral bleaching occurring,” he said.