It obviously should come soon, though, and my expectation would be to see it in a free update.
Just to make it clear, it's not that hard to do it. Here's a very basic example in javascript that took roughly 3 hours of time (this parses enough of the XLSX format to generate a CSV output with a few integers and strings; requires html5 file API to be able to manipulate the file in your browser. Best results on chrome):
http://niggler.github.com/js-xlsx/
source: https://github.com/Niggler/js-xlsx
There's an XLS version as well (doesn't support the full panoply of features):
No reason to release the product without having the data hooks in place. We don't need more silos.