i am talking about solo mining, as my post details... bitcoind is the native clients used for checking/solving hashs created by the various mining clients. while the term "share" may not be 100% accurate, a "getwork" is much the same...
bitcoind gives the miner a merkle root to work with, along with a target, and the miner checks through all the nonces, if none of the nonces result in a hash lower than the target, it asks for more. if it finds a nonce that is lower than the target, it submits the nonce to bitcoind, and it's broadcasted to the network.
in solo mining, as i said, there are no "shares". you either get a block or not. but some miners count imaginary "shares" when solo mining. where a imaginary share is a nonce that meets difficulty of 1.