I know that there was mention of people wanting to do this, but I don't believe I have seen any examples or heard of anyone who has actually got it working.
No, there will not be any additional payment gateways included in version 1.4. There are certainly plans for this to happen in a future release, but as to what and when, we cannot confirm at this time. For the moment it would involve customization on your part to implement a payment gateway of your own.
If you're wanting to know if there are any threads in the forums relating to specifically how to add another payment gateway to JobRoller, then no, there isn't. Not to say that no-one has done it outside of the forums, but there isn't a set of instructions you're going to find here.