An interesting example of this is Dejobaan "1, 2, 3 Kick It! Drop that beat like an ugly baby" which is effectively a mashup of their earlier game, "AaaaaAAaaaAAAaaAAAAaAAAAA!!!" and AudioSurf. They released a prototype to pre purchasers, which then they put on Steam (privately) for ease of distribution.
Leading up to Portal 2's release, with the potato promotion, a still unfinished "Kick It!" was involved as part of the promotion, with users needing to obtain a certain ingame achievement. However, it was not at all made clear to users that this game was still in alpha. Tons of users had a bad experience, and a game that wasn't even really intended to be played yet ended up getting exposed to the games industry at large, of course, with a horrible reception.
Please don't let the delay overly worry you. Here's what the great master Shigeru Miyamoto said:
"A delayed game is eventually good, a bad game is bad forever."
(from:
http://nintendo.wikia.com/wiki/Shigeru_Miyamoto/Quotes).
Of course, you could do 'updates' but you have to make a good impression with your first cut.