Hi Mark, The basic answer is yes, you can write your own connector. We have a partner who wrote a Hubspot connector earlier this year (not EPiServer's). However, there is not a lot of documentation for this currently, so it's a bit of a challenge. We are working to get some docmentation done, but I can't say when it will be available (it is planned for sometime in the next couple of months). There are essentially two ways to do this. One would to write a connector completly from scratch - this would use the current Add-On process that is described on this world site. The other way would be to hook into the MA core that is the guts of the Marketing Automation connectors. This is the part that is currently not documented, but would probably make it much easier to develop your own connector. We have not worked out any licensing terms on this, but it's likely to be an open api of some sort.
I'm looking at implementing some marketing automation using an email system not currently covered by one of the connectors already available, I'm currently at the stage of planning how I might hook it in.
I was wondering whether it would be work implementing some of the interfaces in the connect for marketing automation package and maybe running it as a connector - anyone tried this before?
Also does anyone at EPiServer know what the licencing situation would be for that scenario? Is if the specific connector or just the base package which the license would relate to?