Right now the apiinfo.version call returns the version level of the API, this is good. However it would be nice if there were another call which did a dump of more detailed information such as the frontend version number. I wouldn't expect this call to accept any options, and as the rev level (api version) of the call grows it just returns more info as deemed appropriate. For the initial version I would think returning the following would be useful: (* denotes, if available/trivial to retrieve)
Zabbix Frontend version
PHP Version
Apache Version*
Host OS Info* (linux, distro, distro version)

The main reason for this is to allow third party developers to more easily interface with Zabbix. There are times when something isn't available via the API and a call must be made directly to the web frontend, it would be nice to know what version of the frontend is in use, so as to not make an errant call.

A call might look like the following:

call:

{ "jsonrpc":"2.0", "method":"apiinfo.details", "params":[], "auth":AUTHHASH, "id":2 }

result:
{
"jsonrpc":"2.0",
"result":

{ "frontend":"2.0.0rc3", }

"id":2
}