I noticed that the sample Warlord on the Wizards site for Keep on the Shadowfell is somewhat gimped - he doesn't have Inspiring Word as this link says you should.
From the looks of it, my guess is that you only get Inspiring Word if you chose Inspiring Presence instead of Tactical Presence. They say that the choice has an effect on powers but doesn't say what they are. Plus they don't tell you what Inspiring Word does.
They don't come right out and say it, but look at Guarding Attack in that excerpt, it has a line saying:
"
Inspiring Presence: The power bonus to AC equals 1 + your Charisma modifier."
And Warlord's Favor says:
"
Tactical Presence: The bonus to attack rolls that you grant equals 1 + your Intelligence modifier."
So I've been taking it to mean that your choice makes certain powers
better, rather than closes off your choices of powers (well, I hope it doesn't, that would be lame).