The distinction is important. The 18 USC 2511 prohibits intercepting any electronic communication. 18 USC 2510 defines "intercept" as
the aural or other acquisition of the contents of any wire, electronic, or oral communication through the use of any electronic, mechanical, or other device.(emphasis added) It also includes an explicit definition of "contents"
“contents”, when used with respect to any wire, oral, or electronic communication, includes any information concerning the substance, purport, or meaning of that communication.
Given those definitions, if all Google had been acquiring was the identifying information of the machines communicating on a wireless network, they would have a good argument that what they did didn't count as "intercepting" as prohibited by the wiretap act. However, if Google was actually acquiring the communications passing across the networks, that argument loses a lot of its force. Even worse, in the complaint, the plaintiffs assert that
a GSV [Google Street View] vehicle has collected, and defendant has stored, and decoded/decrypted Van Valin's wireless data on at least one occasion.
While the complaint is written a bit strangely, at least on the face of it, it appears as though the plaintiff's attorney has reason to believe that Google intercepted and decrypted encrypted communications on at least one occasion. If true, it's hard to imagine a more blatant violation of wireless privacy, and it's also hard to imagine a way that Google could escape liability.
So what will happen? Stay tuned. Assuming Google was served with on the 17th (the day the complaint was filed), their answer is due June 7 (see FRCP 12).