[joezydeco]

IIRC, doesn't Heathrow's "free" wifi want a name and/or email address before it lets you onto the net?

Perhaps it's cross-referencing your name w/boarding records for security purposes.

[bjblazkowicz]

Yes, but the flight number is displayed before you submit your email address.

[lnanek2]

Southwest WiFi seems to do this, and unlike Delta it is available under 10k feet, gate to gate. Something about satellite based vs. ground station based.