This website has a nice definition of verbal (or linguistic) irony:
a duality of meaning... that language often carries a double message,
a second often mocking or sardonic meaning running contrary to the
first...
Apparently, irony can have varying levels of subtlety and richness; some double meanings might be more opaque yet brilliant. No wonder the full meaning of irony can be a bit elusive.
I'm reminded of a quote by the composer Rossini, taken from one of his letters:
“I have just received a Stilton and a cantata from Cipriani
Potter. The cheese was very good.”
You heard "keep someone across" the news correctly. It is not so common (evidenced in part by the response you've received here) and you are not the first to wonder about it (as you can see in this wordsmith.org forum as well as this wordreference.com forum)
However, yes, it is currently being used; here are a couple examples (with links):
"Guardian Australia will be back on deck tomorrow to keep you across all the G20 news you can handle." - from the Guardian
"We keep you across events unfolding after yesterday's plane crash in eastern Ukraine." - from BBC World Service
There are several others you can find - all from UK, Australia, or NZ and all relatively recent - simply by Googling "keep you across" (with quotation marks) and hitting "news" (as oppposed to "web"). Interestingly, there are only three pages of results, which would suggest that the history of this expression (or, to be perfectly logical, the history of the use of the expression with "you"), is relatively brief.
The meaning in the examples you can find is, in almost all cases, "keep you abreast of" something, as defined in FumbleFingers post.
However, you will find it used in a slightly different sense here, in a review of LG's G Watch R, which is touted as a...
"...highly sophisticated heart-rate monitor that helps to keep you across your daily workouts." - ITWire
But no, you won't find it in dictionaries and it would seem, given the evidence, that we are witnessing the birth of a new expression. If anyone has evidence to show that this is, in fact a revival of an older expression, I'd love to see it!
Best Answer
Both the examples you've given support this definition from Wiktionary
In the Leake case, Dawkins insists that Leake put words into his mouth, i.e. misquoted him greatly.
I wonder if this has originated or is common usage in Australia as you've given an SMH(Sydney Morning Herald) example and another example I find here which states
and more examples here and here from Australian media articles. One of them defines it thus