BGP community based IP filtering

I've been having an email discussion with a couple of Cisco engineers about
how useful BGP community based IP filtering might be. The following IOS
config fragment might help explain what I'm getting at:

int fddi0
ip access-group community-list 10 in
ip community-list 10 permit AA:BB
ip community-list 10 permit CC:DD

If you are using communities to make your prefix announcements to peers,
this then allows the router to filter incoming IP packets that match your
announcements. Excepting things like CPU load, implementation details, etc
do you think this would be helpful, or am I way off with this?

IMO, this still has the problem of there being a local agreement between the
peers that require them to have a clue or everyone has bogus announces. There
is hopefully going to be a presentation at NANOG by Tony and Yakov about
cryptographic signing of prefix origination. This is a load more work in
several ways, but it does strike at the heart of the problem.