Caliban said:
If you want to ignore the monk's class limitation on wearing armor, that is indeed your prerogative. However, that would have to be house rule, and as such isn't relevant to the question at hand...
I'm not going to rehash to whole argument, but I'll sum up one or two points.
1. It's pretty clear that shields = armor for some purposes and not for others.
2. The Sage (and most agree) stated (but it's not in the FAQ) that shields = armor for monks purposes.
3. It's a legitimate rules interpretation to state that shields do not equal armor for monk purposes - therefore it's not truly a house rule, just a less popular rules interpretation.
Given the past debate on this, I think it's pretty clear that both sides have a pretty good argument, so it's up to a DM to decide which way they want to go. The Sage's rulings have, over time, become somewhat less authoritative by virtue of a number of odd, not well thought-out and/or contradictory responses. One should still give them weight as being the closest thing that exists to an "official" rules interpretation, but one should also feel free to toss them out and still feel like you are following the core rules.
The closest thign we have to truly "offical" rules interpretations is the
FAQ, and I see no mention of a monk not using a shield in there. To me that leaves it, officially, an open issue and therefore not a house rule.
I don't consider other Sage's rulings to be "official" because they are not generally available to everyone and have not been reviewed internally at WotC as the FAQ presumably has.
I see good role-playing, real-life and rules reasons to rule either way on this particular issue.