Vaporware

[Merna]

Vaporware is hardware or software that has been announced, but has missed its release date by a significant amount of time. It includes both products that are eventually released and products that are never released at all.
Vaporware is typically produced when a company is over-aggressive in announcing a product release date. Since technology is a competitive field, one business can sometimes gain an advantage over another by announcing their product will be available first. However, unforeseen delays can push back the release date significantly, leading both bloggers and news publishers alike to dub the product as vaporware.
There is no official length of delay that makes a product vaporware, but the term often surfaces after a delay of three months or more. It also is commonly used after a company postpones the release date for the second time. While vaporware can sometimes work in a companys favor by generating extra buzz, it typically diminishes the product hype, especially after a long delay. When a company has multiple products turn into vaporware, it can tarnish the corporate image and negatively affects the companys credibility with consumers. Therefore, most businesses make a strong effort to release their products on time.
An example of a recent vaporware product is the white iPhone 4, which was announced in early June of 2010, but has been delayed several times since then.

[Sarah]

a computer program that is advertised but is not yet or is never made available

[Cami]

Software or hardware that has been advertised but is not yet available to buy, either because it is only a concept or because it is still being written or designed.

[Merna]

When a company tries to sell you a product that doesn’t currently exist. [But it is] “[coming soon].” Very rarely does it actually ever [materialize].

[Raeanne Dimick]

A game/[software]/thing that does not exist but is being matketed.
Once in a Blue-Moon-Celestial-Aligment-Full-Moon-Good-Luck-Day it may have a
1 in 1 Trilion chance of being [produced].
Example: [Half-Life] 3

[Dave Paprocki]

computer software that is announced but does [not yet] exist due to being stuck in development or being [canceled] [all together]

[Little_Girl]

[Anything] (usually [software], but can be [anything]) that is promoted and marketed without ever actually being [produced].