Update: Valve let us know that Steam now takes care of this issue: "Owners of the retail version of NBA 2K9 for the PC may now install their games without the CD key, provided the disc is in the drive. And those considering a purchase of NBA 2K9 may do so without concern of installation issues related to the lack of a CD key."
Original Story: According to a seven page thread on the 2K Sports forums, the company forgot something important when it shipped the PC version of NBA 2K9 (also, PS3, X360) to stores: there is no CD key to be found anywhere in the box.
"I just located 2k9 for the PC and when i got it, it does not include a cd key but says it needs one to install...what do i do?" asks the starter of the thread, with other posters confirming a similiar situation no matter what store the game was obtained from.
2K Sports has acknowledged the issue, noting that the company is "working hard on a solution." That solution should be posted on this page later today.
Thanks to Tom Tran for the tip.