Is there a definitive answer to this capitalization conundrum?

eBay has a fabulous collection of vintage tube tops. iTunes must now compete with Amazon’s Prime Music.

The Chicago Manual of Style has this to say: “Brand names or names of companies that are spelled with a lowercase initial letter followed by a capital letter (eBay, iPod, iPhone, etc.) need not be capitalized at the beginning of a sentence or heading, though some editors may prefer to reword.” That wasn’t always its rule, though:

This departure from Chicago’s former usage recognizes not only the preferred usage of the owners of most such names but also the fact that such spellings are already capitalized (if only on the second letter). Company or product names with additional, internal capitals (sometimes called “midcaps”) should likewise be left unchanged (GlaxoSmithKline, HarperCollins, LexisNexis).