What the meaning of bitcoin logo?
I think the logo is simply the identity given to bitcoin for recognition just like any other business or product out there nothing more 
Not sure how much degree the B is, I can't remember whether I have ever read this anywhere. The initial Bitcoin logo wasn't this which was later even changed by Satoshi Nakamoto into the current logo of bitcointalk forum. Later on, bitcointalk user bitboy came with the current version though his thread doesn't show the image he posted. Check here- https://bitcointalk.org/index.php?topic=1631.0 though you can check the original; thread here- https://web.archive.org/web/20130524191250/https://bitcointalk.org/index.php?topic=1631.0
1st Version
2nd Version by satoshi, is Bitcointalk logo now.
Interesting write up, so the bitcoin logo had several revisions before it got where it is today,and I see version 1 and version two were all done by satoshi himself but what did bitcointalk user bitboy suggest as I couldn't find anything from his post history because of the image proxy image error nor does dropbox give the images because of error 404 .1st Version
2nd Version by satoshi, is Bitcointalk logo now.