I don't think it's a good idea (I think it's opposite of that) to use not yet closed parts of css3 specification in production. I mean, it's ok as long as it works without it. This code is full of vendor specific prefixes. They only add in size and many of them doesn't have reliable fallback.
Also, these buttons look close to horrible (as in unreadable) in browsers that doesn't support all features used. I only tried quite capable Konqueror but I'm affraid what would they look like in IE7. Another thing is that this is 16kB (uncompressed). 16kB for social sharing buttons that doesn't really stand out that much (as opposed to css(2)-styled buttons) and add no extra functionality to the user.
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I don't think it's a good idea (I think it's opposite of that) to use not yet closed parts of css3 specification in production. I mean, it's ok as long as it works without it. This code is full of vendor specific prefixes. They only add in size and many of them doesn't have reliable fallback.
Also, these buttons look close to horrible (as in unreadable) in browsers that doesn't support all features used. I only tried quite capable Konqueror but I'm affraid what would they look like in IE7. Another thing is that this is 16kB (uncompressed). 16kB for social sharing buttons that doesn't really stand out that much (as opposed to css(2)-styled buttons) and add no extra functionality to the user.
So, please, think twice before using them.
There are fallbacks in place for all the gradients. They look fine in IE7. The compressed size of the code is more relevant than uncompressed.
Then, I would change Yahoo one and Github - http://i.imgur.com/HRN0f.png (I'm hovering over the github one). Google doesn't look so well either.