I have found United posts pretty quickly. Ate out on 3/3 and it was posted some time last week. American, too, is pretty quick.
Northwest is a bit slower, but not too bad -- more like 2-3 weeks. Just signed up with America West to round out some miles, but have not used them yet.

But I was NOT aware that some restaurants participate with certain airline dining programs but not others. Seemed like no matter whose Website I downloaded, the same restaurants in my area (Wash DC) were on there. I will be more vigilant now.

Not too much problem with iDine. Now Hotels from iDine is another story. But off topic.