We are receiving this error only in client orgs that have been upgraded to Winter '11:

No such column '[FIELD - we have seen CurrencyIsoCode and RecordTypeId]' on entity '[OBJECT - we have seen Contact, User, and Opportunity]'. If you are attempting to use a custom field, be sure to append the '__c' after the custom field name. Please reference your WSDL or the describe call for the appropriate names.

We are unable to replicate this in our developer org and the debug logs from the client orgs are not helpful. None of our Apex code queries or references currency fields let alone CurrencyIsoCode and do not query for RecordTypeId on Contact, Opportunity, or User. The client orgs do not have multiple currencies enabled.

This could potentially be a serious issue when the rest of the Salesforce instances are upgraded to Winter '11 this coming weekend.

We have additionally logged a case with Salesforce. Any thoughts are greatly appreciated.