Wow! For only $99 I would get two of them! From what I can tell when looking at the site it is an OEM (or very good copy) of the Psion Revo+. This piece of hardware is worth every single dollar!
Over to the question. There only comes along software for Windows, ofcourse. Sort of odd idea since Psion have marketing their product as the ultimate tool to connect with what every OS on the market... well as long that you ran Microsofts. So the software that comes along wouldn't make your date. But, what You can use is the NetDrive together with the Psion plugins available so I for a start are able to connect with the device via ftp and make backup of files and as well sending over files to work with.
The same group of people working on the plugins aslo works on plugins to connect and share information with Lotus Organizer for OS2 and hopefully other PIM software.
I got the Psion Revo (the one with 8MB ram) but I after seeing this offer for $99 for the 16mb version.... guess that I might get another one just for the fun of it.