Chalk this one up as another way Twitter is changing the political landscape.

In addition to using Twitter as a tool to communicate interest groups' advocacy and messages, it is now also being used to dispatch memos to members of Congress and their offices over specific pieces of legislation.

Take, for instance, National Taxpayers' Union, which tweeted Monday:
NTU Vote Alert: Housing Bill Amendments: ****************************************** National Taxpayers Union Vo..

(For the record, the vote alert is to urge the passage of two amendments that would prevent the nationalization of banks, while allowing well-capitalized firms to repay TARP funds.)