There isn't a whole lot to say about specific climbing conditions on Mt Rainier these days. It's mid fall, it's beautiful, it's quiet. For climbers, the issue revolves around dry glaciers and lots of exposed bare rock (volcanic rock that is). A few of the steeper routes (Mowich/Ptarmigan) may come back into shape, but those are a gamble. Most of the fresh snow is now 4 months past and the new stuff doesn't seem to really accumulate till November (sometimes later).
All that said, if you'd like the mountain mostly to yourself, some of the finest days to climb are happening right now. That's because the weather has been quite good overall (it's predicted to remain so for another week) and the DC remains climable.
The reponses to the Muir Snowfield question are stilll coming in. As of yet, no one has desented from the general observation: the snow and ice on the Muir Snowfield seem to be visibly shrinking! To those who wrote, thank you. To those who didn't... :)