I stumbled upon that word in this blog post.
There is similar question in hacker news, but without a definitive answer.
Google doesn't seem to be much help either.
+7
A:
Deckware generally refers to "software" that's actually just a deck of slides showing how something is supposed/planned/intended to work. In other words, like the "no startup pitches" bit, it's saying "we don't want to see what you plan to build or are starting building, we want to see what you have built, and is now working."
Amber
2010-10-13 02:37:26
+5
A:
It refers to a presentation, that is, a deck of slides. The term is derisive, implying that there is no software at all, merely a presentation about software. Compare to "vaporware".
Ned Batchelder
2010-10-13 02:38:26