Not really sure how this works. Before starting a match do you disclose what faction you are playing, or do people usually go in blind? It seems that certain deck builds are definitely made to combat certain faction, or corp builds. Is there a rule on this, or is it just a discretionary decision left up to the parties playing to decide? How is this handled in tournament play?

In Tournament play you have to submit your decklists prior to the start of the tournament so you have to decide what factions you're playing before hand. You can not switch out decks (or alter the deck you're using) during the tournament.

Casual play is (obviously) casual so I don't think there are any specific rules.

Yeah, it really depends on how picky your casual-play group is. I've played plenty of games where one or both players make a blind choice, and I've also played plenty of games where one player will choose a deck that is specifically targeted against a particular faction and/or identity. Ultimately, it's up to the casual players.

But like frybender said, tournament rules require that your decks be built prior to the tournament, without knowing what your opponents are using.

Ok, thanks guys. Guess I will have to see tonight how they do things at my local game shop here in Portland Oregon.

Have run in Portland! They're a great bunch and very friendly. Beware, however, Portland and Seatle are probably thr most brutally competitive metas in netrunner