Wow...I've heard exactly the opposite. see above post...WAMU has RAISED capital (ie, added creditors) this month. If you're referring to WAMU Assets like home equity loans, commercial loans, etc. Think why would a debtor run away. Let's say WAMU goes Chapter 11...you'd renegotiate your loan at something less than 100%, wouldnt' you?
Unsecured creditors include other financial institutions. Banks (hell, even the biggest credit unions may participate here) lend reserves to each other overnight so that they meet requirements. Inter-bank lending to WaMu has slowed dramatically. In other words, the other banks don't trust WaMu.
WaMu's own unsecured creditors (the people WaMu owes money to, aside from insured depositors) are the ones pulling money, not folks who owe WaMu money.