Welcome to the forums, myst
If by "OS" you mean Android, then you either have to wait for enTourage to update the OS, or you'll have to hack your own firmware. To date, noone (that has posted in these forums at least) has posted a downloadable firmware update, although several have tinkered with doing so. The latter also means you'll likely lose the Reader, and, of course, warranty and support from enTourage...
enTourage has been working on the Froyo update, which
reportedly is coming along well for the Pocket eDGe, and expected on the EE after it's released for the PE. We don't yet know enTourage's plans for Android upgrades after Froyo.