"BitCoin" has
no historical basis. As theymos and others point out, the software calls itself "Bitcoin". The original paper is titled "Bitcoin" and refers to "coins". Here on the forums,
Satoshi interchanged both the capitalised 'B' and uncapitalised 'b' versions for the technology, the software and both plural and singular versions of the currency: I know because I checked before I decided to start using "BitCoin" in my own posts. I wasn't trying to be correct, I was just creating an arbitrary convention for readability like
the one FatherMcGruder proposed in December. I'm not overly attached to it, but it does have the advantage of being unambiguous at the beginning of a sentence. Consider, for example:
Bitcoin rates exceeded....(exchange rates)
BitCoin rates exceeded....(network transaction volumes)
Bitcoin trading could mean exchanging USD for btc
BitCoin trading could mean a type of commerce based on encoding contracts and other data into scripted transactions.
Bitcoin domain names could refer to domain names whose market value is approximately one btc, as in "penny stocks" while
BitCoin domain names could refer to domain names stored in the blockchain via a bitDNS scheme
etc.
For something that has the air of officialness like the "Introduction to Bitcoin/BitCoin" thread I'm quite happy to use whatever the prevailing wisdom prefers. I do think it's quite reasonable for an open-source project/community to change their conventions for practical purposes should they so desire, but maintaining a creator's original capitalisation is also of social value in the respect that it signifies, etc. As I say above, I'm not overly attached to my usage. The readability issue really only comes into play when trying to differentiate technology from singular btc at the beginning of a sentence.