PS: When typing the word "Twitter" they insist you use an upper case T. If you use a lower cast t (twitter) they will come after you with lawyers and sue you for loads of $$$ (apparently they can do this because Twitter is a registered trade mark). This seems a bit pathetic, particularly since, before the bird symbol, Twitter's logo was simply a lower case t.
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They also don't allow the use of their old logo anymore, so G will probably get sued because I posted this picture. 
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