Is there a workaround to gain access to Microsoft's public calendar using Outlook Web Access?
The workaround is on its way—it's called Exchange 2000. Outlook Web Access gets a pretty substantial face-lift, aided by the new Web store and support for public and secondary calendars. In fact, with Exchange 2000, OWA can get at just about any folder or item in Exchange, thanks to the Web store.
For Exchange 5.5, I can't think of any easy workarounds. You'd probably have to create a special mailbox, copy the public calendar items into that mailbox, then access that with OWA. But that would be a pretty clunky way to do it.