PC Tools and Kaspersky both filed Responses to Zango's TRO Motion.  You can access PC Tools' Response here and Kaspersky's here. 

Both are pretty readable from the non-lawyer perspective and contained an array of expected (and likely effective) arguments.  What jumped out at me?  Kaspersky's First Amendment argument.  Kaspersky argues that a TRO would constitute an unconstitutional prior restraint.  Kaspersky argues that a finding that Kaspersky's label is improper must follow a full factfinding (trial).  Courts (due to First Amendment concerns) don't ordinarily silence critics at the early (injunctive) stages.  This argument is most effective for a pure labeling claim.  (Spamhaus is making this same argument in its appeal, which will be argued tomorrow.)  Kaspersky also raises a Section 230 argument. 

On the whole, there's enough there that Zango's Motion for a Temporary Restraining Order will likely be denied.

[Also, Zango switched lawyers, from Corr Cronin to Gordon, Thomas. 

Finally, I have a short piece on cNet on the Zango litigation:  "Spyware Skirmishes:  Spy Versus Antispy".]

Update:  Prof. Goldman comments here.