It should be pointed out, sIKE, that even if we limit it to one counterspell during the Counter Spell Step, you would legally be able to counter a counterspell.
For example, I cast Dissolve on you and you reveal Nullify. As soon as you reveal nullify, we begin the Reveal Enchantment process as detailed in the FAQ. You can think of this as steps within steps. We are technically still in the Counter Spell Step for my casting of Dissolve, but now we also have to go through the steps for your Nullify of:
1) Flip over the hidden enchantment card showing it to all players.
2) Counter the Enchantment: A player may reveal an enchantment or use an ability which specifically allows it be used during this step.
3) Pay Reveal Costs
4) Resolve the Enchantment’s Effects
During the Counter Enchantment Step, I would still be able to counter your Nullify if there existed a spell that could do so. Currently Mind Shield is the only spell that can be used during this step, and it doesn't affect any existing counterspells (since the only psychic counterspell currently is Mind Shield, and revealing a second one on the target would result in the second one's immediate destruction, thus it can't counter the first one). Since we HAVE to follow the steps for revealing an Enchantment, even though we're in the midst of the steps for casting whatever spell prompted the reveal, we could still have counterspell battles.
Personally, I am satisfied with the rules as laid down by Shad0w and the documents on hand. I like having the option of a back and forth with my opponent as we try to mess up each other's plans. I am not saying that sIKE's concern is completely unfounded, however. It is possible in the future for these battles to get out of hand, though I don't think it is possible with the current card pool. Luckily, the design of having a very restrictive Counter Spell Step and an even more restrictive Counter Enchantment step should give us ample tools to keep this from happening.