This very well could be an internet-only fiction, but this rumor has been floating around a lot today. Personally, I think with running back depth being such an issue coming into the season and Keith having such a good showing, this would be stupid, especially in light of Hall's very questionable behavior in the past. But perhaps the Colt's think Clifton Dawson can handle #2 when Addai returns and Hall would help in a game vs. the Pats.:

http://www.stampedeblue.com/story/2007/10/9/8040/03051
"
The lowly Atlanta Falcons have displayed some interest towards former Roughrider Kenton Keith, who is now a member of the Indianapolis Colts. Sources in the Falcons front office stated that General Manager Rich McKay has been in contact with Bill Polian, Indianapolis' general manager about a possible trade, involving Keith and Falcons cornerback DeAngelo Hall. Hall, the Falcons star cornerback, has been displayed some displeasure with the team in the recent weeks and has demanded a trade after their most recent game, a 20-13 loss to the Tennessee Titans."