To all authors of weblogging/journaling tools, documentation engines, Wiki engines, etc.:
The <i> tag is a style tag. It conveys no semantic information. It could indicate emphasis, a quote, a citation, an address, or any number of other elements of text. As such, it is bad. As in the opposite of good. As in, your tool should never, ever, under any circumstances automatically gererate or insert this markup without explicit instruction from the user. Even then, it should only do so grudgingly, and it should insult the user on general principle.
The <em> tag should always be used where emphasis is desired.
The same goes for <b> and <strong>. Just because most browsers interpret <strong> to mean bold, doesn’t mean <b> is shorthand for strong.
Thank you for your cooperation.