Title says it all: if you've somehow become undead, as a ghost or other undead, and you turn undead, as a cleric or paladin, do you also need to make a saving throw for turn undead?
Answers can be from Ghostwalk, but I'd like the normal undead/ghosts.
The simple answer to “do you also need to make a saving throw for turn undead?” is “No,” just because no one ever makes a saving throw against turn undead. Turn undead simply affects any undead that fits within its HD limits (after accounting for turn resistance), no save allowed.
That said, the real question here is “If you're undead and you use turn undead do you turn yourself?” and that one is harder. Ghostwalk is also a weird, weird book that changes a lot of the rules—it’s really probably better thought of as a separate d20 System game than a D&D 3.5e supplement—so we’ll basically have to double-check everything to see if Ghostwalk changes it.
But the short answer is “RAW, arguably ‘yes,’ but it’s very hard to make the case that this is intended or desirable.”
RAW, the argument basically centers around whether the distance between you and yourself is treated as 0 or as simply undefined. That is, if you are a turnable undead creature, do you count as “the closest turnable undead,” or does the fact that “close” refers to a distance between two objects (and is thus undefined when you are referring to a single object) mean that you don’t count? That argument isn’t actually decidable: either of those statements could reasonably be true, and the rules don’t tell us one way or the other on it.
You’ll see this come up a lot, e.g. here. I can’t prove a negative, but hopefully the fact that others also discuss this as a kind of “open question” gives weight to my assertion that there is no rule for this.
But if you rule that you can, it doesn’t make any sense. If you are turned, “[you] flee from you[rself] by the best and fastest means available to [you],” and there just isn’t any way to comply with that directive, and it’s not at all clear what you’re supposed to do instead. The rules do say that “If [you] cannot flee, [you] cower,” but you can flee here—it’s just undefined where you should be fleeing. You could rule that it still applies, but it’s hardly spelled out.
And realistically, the authors almost-certainly never gave this situation any thought. It’s not that they didn’t consider undead clerics—they did, at length—it’s just that they assumed that all undead clerics would be evil and rebuking undead, not turning them. In fact, Libris Mortis page 35 even claims that “A cleric who becomes undead loses any ability to turn undead, but gains the ability to rebuke undead,” which is a weird statement from a book that explicitly wrote a way to become undead without becoming evil, and in any event contradicts the statements in the cleric class description (which have you turn undead if you’re good, or if you’re neutral and choose it, with no reference to your type). Even if we buy it, though, there are still plenty of non-clerics with the ability to turn undead (e.g. the core paladin, which seems like a bizarre thing for Libris Mortis to overlook here). But it shows what the developers were thinking—and they were thinking that all undead clerics would be rebuking, not turning.
Rebuke undead explicitly allows you to bolster yourself, where bolstering undead is an alternative option to rebuking them. It’s not at all clear that you automatically affect yourself (and so use the bolster option because clearly you don’t want to cower), or if you can choose to bolster yourself but otherwise you’d just be skipped.
Finally, we have to check back in with Ghostwalk, and sure enough, it does change things a bit—because Ghostwalk eidolons are outsiders, not undead. The book even explicitly says on page 5 that when an ignorant cleric tries to turn or rebuke them, “the targets usually just chuckle or scowl or sigh.” So a Ghostwalk cleric doesn’t have to worry about this.
