Can customer comments be printed on invoice?

Is there a way to make the 'customer comments' show up on the invoice when it is printed out? I've been caught a few times now when a customer puts something important about there order in the comments section but I dont see it until after I've sent the order and I'm doing the order updates as thats the only time I look under 'edit' for each order.

The comments that customers enter on the shipping and payment checkout pages do show up on my invoices, as well as the packing list. Are those the ones you mean?

Yes thats the ones I mean. They have never shown up on invoices for me, don't even show up under 'orders' in admin. The only time I see them is under 'edit' or on the email notification. I'm using V1.3.7

Hi there
There is a switch in admin to make them appear from 1.3.8 onwards. For 1.3.7 you need to change the code. I did this a while ago and it's quite easy. Do a search on order comments and you should find the post that contains the code you need.