If you post in detail, you can use a user-defined Journal Reference in Configuration to include the Batch Number.  Unfortunately, you can't use this option if posting in summary, which is what we do.  Thus, I'm voting for this as well.  Accountants need to be able to identify the Batch (i.e. deposit) that a gift was a part of when reviewing the transaction in the GL, and be able to group all transactions, by Gift Batch Number, in the GL in order to reconcile to the bank.  Thus, please open up the option to use the user-defined Journal Reference in Configuration when posting in Summary.