Amazingly, I have never received any notification from the buyer's mortgage broker automatically.
I am sure if you provide that service, the agents will love that. However, I do get pre-apporval letters from the mortgage broker, so I am not sure it that counts a busiess card/follow up fax, or intruduction letter. Also, I am not quite sure what you meant by 'New' purchase transaction. Do you just inform the L.A. when the contract first went into escrow, or do you notify both listing and purchase agents along the way?
When you are a listing agent, you are always worried about whether the loan can go through. The worst part is when the mortgage brokers do not return your phone calls - yes, that have happened to me, you automatically assume that there is problem with the loan; which can add strain to the transaction, whether it's true or not. So, communication is very important.
If you provide this kind of service, I am sure you will be loved by all the Realtors. I know you are an expert on this but I am sure you have already received O.K from the buyers to do so.
Also, along with the problem I stated above from the listing agent side, if there there is problem with the loan; and it is way before loan contingency removal time, and buyers and buyers' agent are aware of the problem and are trying to work that out somehow. They might not want to get the sellers panic at that stage. But if you are contacted by the listing agent, I think you want to convey all that truthfully, with the clarification that the problem is being worked on. Either way, I think you want to consult the buyer agent on how to communicate that fact.