https://www.facebookbrand.com/dos-donts
http://www.apple.com/legal/sales-support/certification/docs/...
Page 12 -- No go "Do not use the Apple logo alone in channel affiliate communications, including web pages." (I.e. You can't just show the Apple Icon)
https://www.dropbox.com/branding
Yahoo's icon actually doesn't look like Yahoos brand icon so I would call that one a pass
http://developer.android.com/distribute/googleplay/promote/b...
Pretty much no restrictions for the robot-- accept you need attribution according to Creative Commons 3.0 Attribution License.
http://developer.linkedin.com/documents/branding-guidelines
Linked in is specific in what the logo can be used for, instead of what it looks like. So this font is fine, but even in the preview the logo should point to a linked in page or profile.
http://www.youtube.com/yt/brand/using-logo.html
The logo the author used isn't the one trademarked-- fair use here.
"Use only the official, unmodified files to represent our brand." So this ones a no (though it's confusing... what if the author used the original glyph? Is conversion considered modification? I suppose)
http://www.microsoft.com/en-us/legal/intellectualproperty/Tr...
Unless that glyph isn't trademarked it's not okay to use, even the logos mentioned state:
"Do not use in... Web sites for any purpose except pursuant to an express written trademark license from Microsoft."
https://en.bitcoin.it/wiki/Promotional_graphics
Bitcoins assets are fair game.
Seems to be okay, since colors are 'encouraged' and the gylph is shown as ones that are okay to use.
http://www.reddit.com/about/alien/
Absolutely no go: "We require a license to use these logos in anything outside reddit, both for free and for profit."
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Summing up here I was surprised to learn that the restrictions are more stringent than I thought. If I were the author I'd clean up the alternate version and remove the Glyphs that aren't specifically allowed, otherwise anyone who uses your font is technically opening themselves up to trademark violations.
IANAL but as far as I understand it, the purpose of a trademark symbol is to save you from having to send C&Ds to unwitting infringers. Your trademark doesn't lose its status just because you left of the registration symbol.
In all seriousness, they are claiming copyright over an icon that is clearly meant to represent a brand's copyrighted and trademarked logo. Then they are rereleasing that logo under a MIT license. I have never gone to law school, but I can't imagine that Apple's lawyers will be thrilled by that.