Microsoft filed a notice of appearance Tuesday asking the court to send all notices and pleadings in the case to an attorney representing the company. Notably, the notice was entered on behalf of Microsoft and a wholly owned subsidiary, Microsoft Licensing.

The attorney named in the filing is Joseph Shickich Jr. of Riddell Williams in Seattle. I've asked him and a Microsoft spokesman to comment on the company's interest in the case. I'll update this post depending on their response.

(Update, 10:05 a.m.: A source familiar with WaMu's IT management tells me WaMu had negotiated an enterprise software agreement with Microsoft worth nearly $40 million in 2007 to be paid over three years. The company probably just wants to get paid. A bit more interesting: The source says WaMu and Microsoft worked closely on new technologies, meaning some intellectual property could be in play, too.)

(Update, 10:23 a.m.: Microsoft spokesman David Bowermaster responded with this statement: "We filed a notice of appearance because we have existing contracts for software licenses and consulting services with Washington Mutual and we want to make sure those contracts are properly administered through the bankruptcy process.")

WaMu's Chapter 11 bankruptcy filing on Sept. 26 listed more than $8 billion in total debts.

Several other entities have filed appearance notices in the case, including county government agencies and vendors including Tata American International Corporation and Tata Consultancy Services Limited, which are arms of the Indian IT outsourcing giant Tata Group.

The Puget Sound Business Journal first reported Microsoft's filing.