The
only problem I can see is that just the
"To Do" application features would be too miserable to bother about implementation of collaboration on more than one kind of system.
Anyway, if you install some well-known RDBMS on Linux or Windows, it can access the database in transactional manner on all kind of systems; likewise, if you implement a Web Service on Linux or Windows, you can access it on all kind of systems. Also, if you install Mono on Linux and .NET on Windows, you can develop collaboration software using classical .NET remoting of WCF which would work transparently on all systems. Finally, if you develop a Web application of one kind of system, presumably using 3-tier architecture, the client software could be run an any of the popular Web browsers and hence be used on any system.
That said, there are no serious technical barriers to organize collaboration between different kinds of systems. In all cases, you just need a server and… development time. Again, the question is: does it make any sense to bother about development any software just for the "To Do" application.
In my opinion,
it makes no practical sense at all. You can, and actually need to use much stronger system, such as
project management and/or
issue tracking system, see
http://en.wikipedia.org/wiki/Issue_tracking_system[
^],
http://en.wikipedia.org/wiki/Bug_tracking_system[
^].
There is a number of robust multiplatform systems you can use. I would also require such system to be Open Source. See what choices you can have:
http://en.wikipedia.org/wiki/Comparison_of_issue_tracking_systems[
^].
I personally would recommend to look at Trac, which is nearly minimalistic, but its benefits include Wiki technology and nice integration with Subversion, see:
http://en.wikipedia.org/wiki/Trac[
^],
http://trac.edgewall.org/[
^],
http://en.wikipedia.org/wiki/Wiki[
^],
http://en.wikipedia.org/wiki/Subversion_%28software%29[
^],
http://subversion.apache.org/[
^].
I could also recommend Bugzilla, see:
http://en.wikipedia.org/wiki/Bugzilla[
^],
http://www.bugzilla.org/[
^].
—SA