IAALBIANYL, so I will leave whether or not this would be operationally useful to those smarter than me, but from a legal standpoint, one should be aware that operation of a system like this as far as the United States would likely result in additional charges for obstruction of justice[1].

It is by no means unusual for the government to fail in the prosecution of the original crime they investigated, but succeed in convicting a defendant for obstruction. (See, e.g. Martha Stewart[2]). In fact it is not at all impossible (though not likely) to imagine a scenario in which someone committed no crime, was running a utility like this, and was eventually charged with obstruction. Say I'm Brian Q. Krebs, some nice people on the Internet decide to swat[3] me confusing me with someone with a similar name[4], police enter my house, swatd deploys and ambitious and creative young prosecutor decides to charge me with a violation of 18 USC 1519. Might not succeed, but boy will he get some press.

As always, the best advice if you are going to engage in a wide-ranging criminal conspiracy is to make sure you have some goofy-reasoned memos from DOJ lawyers approving your activities[5] and Congress on call to provide you retroactive immunity[6].

[1] 18 U.S.C. 1519 (or 1001 or 1501, or 1510) - http://www.law.cornell.edu/uscode/text/18/1519

[2] http://en.wikipedia.org/wiki/Martha_Stewart#Stock_trading_ca...

[3] http://en.wikipedia.org/wiki/Swatting

[4] http://krebsonsecurity.com/tag/swatting/

[5] http://en.wikipedia.org/wiki/Torture_Memos#Letter_from_John_...

[6] http://en.wikipedia.org/wiki/Amnesty_law#United_States or http://en.wikipedia.org/wiki/Foreign_Intelligence_Surveillan...