The Ultralighter does this trail as an annual pilgrimage.
The summary of his 2009 trip report:
You probably don’t want to try the Loowit Trail now. Maybe 2011 or later, if the Forest Service does a bunch of work. Even Lava Canyon is impassable, unless you are very, very bold. So for now it’s the north half of the mountain or the Smith Creek valley, rewarding in their own ways.
He survived his most recent 33mi circuit. But barely.
This trip is no longer an adventure. It is an ordeal.
read the entire trip report
You can still climb Mt St. Helens.
But don’t plan on doing the Circuit until the damaged trail has been improved.
besthike.com 
I came across your trip report while researching the Loowit Trail in preparation for this next field season. WTA received a grant to lead volunteer work parties to restore the most impassible sections of the trail. This year (2010) we have at least 5 work parties planned. The trail is likely to need much more than that. But our hope is that we can get some more people interested in the trail and in coming back next year to give back to trails.
anyone interested in joining a work party or getting a group together to partner on a custom trip can contact me at ryan@wta.org.
-Thanks, Ryan