Some eBay sellers will stipulate a prolonged delivery date to accommodate the pre-order time lag. I recently purchased something on Aug. 10, not realizing the seller didn't have the item in stock (therefore a pre-order) and the latest date in his delivery estimate was Oct. 10 (I assumed this was due to the seller being in France and I'm in the US).
I called eBay, who confirmed that the latest date I could file a non-delivery date was one month after that latest date, which would have been Nov. 10 (and I asked the agent to confirm this at least twice!) In my case, the estimated delivery date range was a key factor as far as buyer's protection was concerned. So, what I suggest for anyone who makes a pre-order purchase on eBay is to call eBay afterwards and have them confirm the latest date you can file a non-delivery complaint, just in case. Oh, and yes, as others have said check the feedback rating!