I have a world-wide concern with "blue globe" earth images, and a USA-related problem with "blue flame" logos.
Guidelines explicitly dis-allowed the use of elements which are already in use (by Mandriva, KDE, GNOME and one or two others.) But the "any other obvious trademarked/common logo" is open to interpretation, and I think that we should explicitly dis-allow "globe earth" logo elements in shades of blue. Firefox is possibly the most popular "open source" software of all; and they've been using the blue earth background ever since they crawled through the Phoenix --> Firebird --> Firefox mess. - - - - - I also hate the blue flame image (in nearly all of it's many variations). People on other continents may not know this, but the emblem is _widely_ used in USA advertising. Not just one company, either: It's shared among all makers of gas appliances and vendors of gas (piped-in natural gas, and tank-stored Liquid propane too). Natural gas gas supplies are abundant and inexpensive here- typically only 1/3 the cost of electrical resistance heating, and we've got at least 200 years worth left of recoverable natural gas left.) In addition to advertisements promoting specific products and suppliers, there are additional ads bought to emphasize that it burns much "cleaner" than coal. (These are the most numerous of all advertisements.) So, in the USA, it really DOES look like we're trying to sell kitchen stoves, or water heaters, or burners for heating homes, or gas appliance usage in a general way.
