WotC Article said:A conjured creature is a minion (MM 282). It has no healing surges and cannot be healed, and it cannot gain temporary hit points.
I wonder if this is a sign of upcoming errata for minions in general?
Finally! I can has stats for a badger minion for my Gnome strike groups!
I doubt it. I think it's just an exception. They're saying that the conjured creature is exactly like a minion, and then they list exceptions to the normal minion rules as they apply to the conjured creature. What's that basic rule they've been saying for 4e? Something like general rules and then specific ones? This is a perfect example of that.
I haven't looked at the MM, so I don't know if enemies have abilities that grant temporary hit points, but players definitely do. I think this is a special note so that minions don't become non-minions by virtue of gaining temporary hit points, which can increase your total over your normal maximum.