http://www.dictionary.com/browse/journal:
1. a daily record, as of occurrences, experiences, or observations[...]
3. a periodical or magazine, especially one published for a special group, learned society, or profession[...]
4. a record, usually daily, of the proceedings and transactions of a legislative body, an organization, etc.
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Although, a company publishing a peer-reviewed scientific journal like Nature would be surprising. So maybe that isn't the common interpretation when they see the title. Maybe it isn't totally misleading. I guess I'm split on it. :)
It isn't 2: This isn't what would be generally understood as a 'periodical' or 'magazine'. It doesn't even resemble the trade publications that are often published by larger businesses.
It certainly isn't 4 - Apple isn't giving away terribly detailed accounts of their research activities.
The word "journal" comes from french "jour" which translates to "day".
The word blog comes from log which original comes from tabular record-keeping of ship speed.