Gabriel,
Thanks for your time developing your module and for contributing it to the community. I'll download it as soon as I get my machine ready to install ez publish.
Why didn't you use content classes/objects for it? Right now it is rather "isolated" from the other content objects and hence difficult to extend and you loose the benifits of the rest of ezpublish (related objects, versioning, ...).
But of course, it is already useful as it stands now
Basically, I was bored one day (note that I don't really do anything this summer except waiting for university to start in October so stay tuned for other modules) and decided it would be rather easy to write a calendar. Turns out it's far from trivial (ever noticed how screwed our time system is? There are days of 86400 seconds, weeks with 7 days that don't give a damn about month boundaries and to top it off, months aren't always the same length either) so after I had the time stuff sorted, I was already way over the time I had estimated.
Additionally, I had to realize that a sane display is hard to do without CSS and a lot of custom code (there are about 150 lines that render week and day pages) and the content module doesn't really provide very much to enable you to do this kind of stuff without a lot of cumbersome templating (I find it's orders of magnitude easier to just code it in standard PHP, it's not like anyone would go change the design considering how hard it is to come up with a sane one anyway).
Furthermore, I didn't feel it makes a lot of sense to have versioning in a calendar and it's much easier to just use ezDB instead of ezContent objects as I know SQL and the API documentation is rather thin on big parts of the backend stuff that is responsible for actually doing something.