But Wyrxian is surprisingly open about "future possibility:" he does say that while Blizzard could allow us to send items between factions if they wanted us to, they also wanted to leave things open just in case the functionality came into view in the future. That doesn't mean we can expect a change in the next patch, but it does seem to mean that Blizzard is still open to the "possibility." You'd think it be tough technically (character inventories are all over the place, especially cross-server), but considering that we can now have cross-server battlegrounds, all it would probably take is a tweak to the in-game mail system. One character sends an item, another character receives it.
And really, the only possibility that might come open is just ease-of-use -- that's why BoA and Heirloom items are in the game already, and if Blizzard determines that it would be easier to have you share items between your characters' factions and servers (perhaps if they upgrade the character re-customization feature to include a faction change?), then it will likely happen sooner or later.