I did not know this. The Bolt Action rules are available for the Kindle as an eBook and in some cases are significantly cheaper than the printed versions.
Though I prefer real paper books when playing games (and for filling the bookshelf) I can certainly see the potential usefulness of having rules and source books on a tablet device.
With lower prices on the Kindle books I can also see the value in getting some of the source books especially those for those nations used by your opponents.