I may be late to realizing this, but it appears as though the 5530890 patent is under request to be reexamined. The reqest was filed by Fish and Richardson P.C. on 1/16/09.

Looks like it's been assigned to POKRZYWA, JOSEPH R according to the Application Data page. Says decision on whether to proceed with re-exam should be out by 4/16/09.

This may be old news, but thought I'd post it since I just realized it. Hopefully this comes back as denying the reexam request and saves us all some headache.