If user goes to Project Explorer, expands project "hello-world", expands Debug folder and double-clicks hello-world.elf then new editor window appears showing binary contents of the file.
It could show assembler listing.
This issue was mentioned in 2006 on mailing list:
http://dev.eclipse.org/newslists/news.eclipse.tools.cdt/msg11793.html
http://dev.eclipse.org/newslists/news.eclipse.tools.cdt/msg11834.html
As far as I can see the basic functionality is already in CDT, we would just need to override one class which has "objdump" and its parameters hardcoded.
I will check this before the next release.