Oh yes, I am very excited for this! However not everyone uses google for calendars so it would be great to have CalDAV integrated into this for syncing with other online providers. This is something I have wanted to look into but just don’t have the time.
Also please look at the way that the People application saves Person files for contacts. Information is saved as attributes to the file, so it is fully query-able (is that a word?) by the file system. This also allows other applications to easily interact with Person files, so you have multiple applications all using the same data set. That is a truly unique feature of Haiku (from BeOS) that should be leveraged.
Good luck, and we are all here to help when you have any questions!