Do you mean the item description? What version are you using? The reason I ask is that the distributions on receipts/invoices are summarized per document for posting to the GL which is why generally it has been difficult to get the line item information tied to the GL directly (since there could be multiple lines flowing in to one debit or credit). One reason for the difficulty was that users could modify the summary distributions (making it difficult to track back to the line items).
However, with GP 10 there is now a constraint (as of SP 2) that the summary distributions can no longer be edited, to allow for better traceability of distributions and line items (primarily to assist with inventory reconciliation to the GL).
So, long story short...there is not a way to get it to do that automatically...but with the new inventory trial balance report available in GP 10 SP2 there may be a way to report on those descriptions tied to the GL.