IS THIS A POSSIBILITY:
MAYBE the large coporations don't even know
that their generic .mobi is up for auction at sedo?
I was viewing all of the auctions, and most of the GREAT names only had
400-500 visitors the listing.
I KNOW that sedo doesn't do much effort in contacting serious end
users to participate in the auctions.
If I am wrong, certainly correct me... and I'll cower down in shame 
But honestly, is sedo contacting ANY serious end users when
premium names are coming to auction?
I know that the few premium GENERIC .com's that I've listed
on sedo auctions... they didn't pick up the phone at all and
try to reel in a big fish. My opinion:
WHY haven't the large corporations jumped in yet?
3 things...
1. they are waiting to see if it catches on (and if it does, they certainly have the money to spend to buy the .mobi they want... no matter WHO owns it)
2. they might not even know that their desired .mobi is being auctioned off, since sedo doesn't prospect large buyers very well
and
3. it took them a while to see the value in a generic .COM so I doubt
they'll jump right in the generic .MOBI... it might take time.
Again, if my thinking or ideas are 100% wrong...
it's just my opinion
and I don't feel strongly one way or another.