Personally, the thought of any government organization demanding records without a warrant is abhorrent.
However, since the entire point of Twitter is to make your tweets public … then what is there to subpoena? They’re all out there – visible to the world… Unless the user has deleted them (and, from my understanding, they are “real” deletes (unlike facebook “deletes” which may or may not go anywhere)).
So, NYPD – why are you not just looking at the tweets that are available publicly? Why are you trying to demand data that may or may not exist, and without a warrant?
Lastly, to Mr Winer’s comment that “the government has no business investing taxpayer dollars in private companies”: there’s a couple big problems therein. First, since it was in reference to the Library of Congress, we should make sure that in addition to not “investing” in archiving tweets, they also not invest in archiving books, journals, newspapers, etc – after all, those are also coming from “private companies”. Second, if the government shouldn’t be investing taxpayer dollars in private companies, then where, exactly, do you propose the “government” get what it needs to operate? By fiat? By dictatorial claim? No – those aren’t good public relations moves. The government needs to obtain the services and goods it needs to continue its functions from private industry (or we need to abandon this whole ‘capitalism’ thing and go for a pure central economy wherein all produced goods and services are provided by the government).