We've just released an update that enables every player in a public game to buy items and build/remove barricades and mount weapons. However, cash spending is limited to how much a given player has earned during the night and is displayed during the day in parentheses next to team's cash. This limitation doesn't apply to the game's host, he or she can spend all cash that has been collected by all players.
We've also added option for the host to ban people from their game. This option can be accessed from the pause menu.
We also have a status update on Trading Cards - the game is now eligible to have them and as soon they reviewed by Valve everyone will receive them retroactively - if you've already spent enough time in the game to receive the Trading Cards, you'll get them once they are approved by Valve.