In testing my sandbox for the upcomming winter 12 release I have found that existing code has been broken (continues to work in production, coded exactly as it is in the sandbox).

It appears that aggregate functions can no longer be aliased according to the developer API documentation as found at:
http://www.salesforce.com/us/developer/docs/api/Content/sforce_api_calls_soql_select_groupby_alias.htm

Provided are 3 SOQL queries demonstrating what I am experiencing.  Two which should be run from the Sandbox and the third from production.  I have indicated the outcome of each and the error received when applicable.

Failing from Sandbox (Invalid field Total_Cost__c

for (AggregateResult ar : [SELECT Sum(Total_Cost__c) Total_Cost__c FROM Service__c WHERE Quote__c in :listQuote GROUP BY Quote__c, Service_Category__c, Product__r.name]){
  system.debug(ar.get('Total_Cost__c'));
}

 Success from Production

for (AggregateResult ar : [SELECT Sum(Total_Cost__c) Total_Cost__c FROM Service__c WHERE Quote__c in :listQuote GROUP BY Quote__c, Service_Category__c, Product__r.name]){
  system.debug(ar.get('Total_Cost__c'));
}

 Success from Sandbox

for (AggregateResult ar : [SELECT Sum(Total_Cost__c) Total_Cost__c FROM Service__c WHERE Quote__c in :listQuote GROUP BY Quote__c, Service_Category__c, Product__r.name]){
  system.debug(ar.get('expr0'));
}

My questions are:

1. Are my results something that I am doing incorrectly?

2. Are we really losing the ability to alias aggregate functions in our SOQL?

3. Is there anywhere that this change (any any others, in this or future releases) is documented?

4. Are there any better ways of handling this change, besides ordering any/all aggregate functions and accessing them by their exprn position?