I have not done it yet but it's on the list.
Biggest issue is the TCP stuff. With a Pi you can add a ZWave daughterboard and go from there.
Talking TCP to the HAServer or ZWave Serve on the Almond+ will take a little work, but yes folks have done something along those lines.
iirc there were folks monitoring the port to read info and others who were sending info before some security was implemented. Forget what the integration was, HAB maybe or OpenHA, something like that. It's here in one of the threads.
Start with something simple like a Binary Switch.
The Arduino can run some OpenZ-Wave stuff and report back as a sensor.
On the Almond+ side, created a custom sensor/device by adding it to DeviceList.xml.
DISCLAIMERNOTE: This is not a supported action and may cause your Almond+ to panic, brick or otherwise to bad things.Having said that, not such a big deal, just backup your Device (d/l image to PC) and backup the DeviceList.xml file.
As for more complicated sensors, so long as the Class is supported by Almond+ and you can implement the ZWave stuff on the Arduino side, yes it can be done. You can get a list of classes from the links in this thread.
http://forum.securifi.com/index.php/topic,3426.0.htmlI have to grab a couple shields for my 'duino to get started on this and I'm testing several products this week and next, so it's on the list, just a few weeks out at a minimum.