Here's the bottom line: If Littleton makes the Red Sox opening day roster, the Rangers could potentially get a second player. Littleton is out of options, so if he doesn't make the Red Sox roster, the Rangers would probably just get a little bit of cash.
Of course, it is a lot easier to slide a player without options through waivers at the end of spring training (see, e.g., Robinson Tejeda and Nelson Cruz) than now. So even if Littleton doesn't make the BoSox roster on Opening Day, he could still stay in the organization.