The matter about google indexing instawallet's pages was brought up on Torwallet's thread, yes.
As rjk said, if you keep your url safe (not post it anywhere online) google can't find it.
I gave an example. The right person will understand this.
Assertion 1 :
Your search yields approximately 19 URLs.
There are over 250,000 different wallets at Instawallet.
Assertion 2 :
Google does not magically index hidden wallet URLs.
Make your conclusions.