Little bit of insider info
In my line of work I've probably seen hundreds of NSW/AFP interception warrants for the period 2007 to 2010. Boy do I hate checking warrants!
A real difficulty is they way the Telecommunications Interception act has been changed progressively, so in each case I have to figure out what the appropriate law was at time.
At one stage in 2007 the cops were obliged to get a warrant for any intercept, except, that they could just ask the Telcos for the information anyway without warrant. Section 177 amendment at the end of 2007 means that now Telcos can give any information to the cops without warrant, but not if the cops ask for it (amazing but true)
I've seen plenty of Telecommunications Intercept warrants (record voice and metadata). Surveillance warrants (follow, video and bug the suspects), Stored communications warrants (harvest the switches for SMS & metadata post-facto). What I haven't seen yet is data interception warrants.
I actually think data interception should be used more often. The Police cases I see are easily attacked because of a lack of belts & braces approach to raids. (And I work for the bad guys..)