That's interesting. I tried for quite some time to find it (on both one friend's MBP w/ Mountain Lion, and another's with Snow Leopard, in case it wasn't present in the ML App Store), but couldn't. The support guy said they'd removed them from the store. I wonder if it's because you've already downloaded it on that hardware, or are running Lion currently (are you?)?

At this point it's academic; the laptop is gone... but if I did something wrong I'd definitely like to know :).

Ah, no, I figured it out. You can make Lion re-appear in your Purchase tab by option-clicking on the Purchase tab icon. I did that some time ago and now Lion is permanently visible for me.

Who thinks of something like that? If you do something stupid like that, at least support should know about it. For shame Apple, for shame! m(

I remember already being annoyed about that some time ago.

Thankyou for that. That'd have saved me a lot of drama :).