This week's "New Yorker" has a fairly well written article, "The Climate Fixers," by Michael Spector on real geoengineering research, it's potential and its risks. He is a regular contributor, but I am not sure what his scientific background is, if any. Oddly enough, he does not even mention the the aluminum/barium/strontium chemtrails approach, discussing mainly schemes to inject sulfur dioxide in the upper atmosphere. This could have the unintended effect of feeding the conspiracy theorists, who will ask why he avoided that subject. Maybe he isn't even aware of the chemtrails conspiracy theory. The print copy indicates that there will be an online conversation with the author, but I haven't been able to locate it. http://www.newyorker.com/reporting/2012/05/14/120514fa_fact_specter
It's a pretty lightweight article. But sulfur is a much more discussed option than aluminum oxide, etc. The reason being, as noted in the article, it's what nature does naturally with volcanoes, so we have some idea of what happens if we do it artificially.