In the modern era, at least, it's not strictly true that journalists were busy transcribing speeches; it's standard practice for a person giving a speech (especially in politics) to give copies of the speech text to the press, usually before the speech itself. Typically it's provided under an embargo (http://en.wikipedia.org/wiki/Embargo_%28journalism%29), so the reporters can't actually report on it until the speech is over, but the extra lead time lets them start working on their stories early.
That's how you can see talking heads on CNN saying "we're told the President will talk a lot about taxes tonight," say, in the run-up to the State of the Union address -- they've gotten a copy of the speech from the White House, under an embargo. So they can't print the text of the speech right then, but they can allude generally to its contents.
That's how you can see talking heads on CNN saying "we're told the President will talk a lot about taxes tonight," say, in the run-up to the State of the Union address -- they've gotten a copy of the speech from the White House, under an embargo. So they can't print the text of the speech right then, but they can allude generally to its contents.