A product that doesn't exist yet. By implication, it will ''never'' exist; it's not even in development. But somehow that doesn't stop the salespeople selling it.  [Not all vaporware is completely nonexistent; software that is in development and has been announced somehow, but doesn't have a firm availability date and feature set, is often considered vaporware.  Software not-yet-released, but with a promised ship date in the near future (and an expectation that it will actually be delivered) often escapes the "vaporware" label]

Large software companies often become famed for 'VaporWare' production - they announce competing products days after rivals release a product in order to induce FearUncertaintyDoubt, then go off and start work on the product...
-- KatieLucas

''Tactics like that got IbmCorporation in trouble with the anti-trust authorities.  Nowadays, companies aren't generally blatant about pre-announcing vaporware; instead word gets leaked to the trade press.  For example, people have been talking about WindowsVista for years now; nobody knows for sure when it will ship or what it will have when it does.  It might end up like MicrosoftCairo--as pie in the sky''

''And if the FearUncertaintyDoubt is enough to kill the competing product (and if the competing company don't have a lot of cash, it probably goes down with the product), they don't need to really finish the product.  At best a half-baked product is released and will be forgotten 6 months later.''

Even at that both these still ignore the 'NEVER exist' criteria. The term vaporware like the products it describes is a bit ill defined and still in the pipe. I guess by now any reader who has not already experienced VaporWare is starting to get the idea. 
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''My family is thinking of getting a new Windows version. But we don't want to buy XP because WindowsVista is going to come soon. Then WindowsVista gets delayed. So, I guess no Windows version for a while... did MicroSoft just VaporWare itself?''

ScamPattern