I noticed today, due to some exceptions, that sites that do not perform in beta can be closed and thus removed from /sites.
If you persist data, you will need to check your data every time you pull /sites.
8-\
I would suggest adding a site.state, closed, and keep the site in the list for a short period of time to allow an intelligent response to the event.
response to kevin
This is assuming that sites behaves perfectly. If, for any reason, sites does something like returning an empty array, or a malformed site, automated processes will erroneously delete or disassociate data.
Where as if an explicit indication that the site is removed were present appropriate and proactive action could be taken.
This is another case where a little bit of compromise in providing fault tolerance upstream would be of great benefit downstream and easily justify a few extra bytes in the /sites response.
see http://area51.stackexchange.com/proposals/614/electronic-gadgets
