I just wanted to share a story.
Husband and I went to a Wintergrasp, I on my big bad (okay, cute and plump) PVP druid and him on his DK. One of our guildmates, a warlock, was also in the raid group.
(For those who don't know, Wintergrasp is world PVP, not a battleground, so different rules apply. You form a raid to share kills.)
This guy in the raid, we'll call him Mr. Undead, asks for a summon because he's stuck in Dalaran's well and the GM isn't responding.
It was a perfectly reasonable request, though you might wonder why he joined the WG raid if he couldn't move. I suppose he hoped a summon would be available. Also reasonable.
I said "working on it" and asked my fellow guildmate to come over to husband and myself so we could summon Mr. Undead.
I had Mr. Undead targeted so saw him hopping around when he accepted the summon. I was pleased, I assume he was as well, and we sat to wait the next eight minutes for the battle to start.
With one minute to go, as I'm trying to share WG quests, I see Mr. Undead in chat again. "Can I get a summon plz. I want to pWnz." I shift-click his name.
He's in EASTERN PLAGUELANDS.
I replied "Didn't we already summon you?"
And he stayed in Eastern Plaguelands for the whole battle.
When one of my guildmates wanted in the raid, I worked out the weird letters in the raid leader's name (had to /who Wintergrasp and right-click to just whisper the guy, since he didn't read raid chat >.<) and said "Mr. Undead is in the Plaguelands. Can Guildmate get an invite?"
And he did.
So, there's a lesson for you boys and girls. If you ask for a warlock summon to something once, DON'T run off to the other side of the world and expect a second one.