private plugins? oO

that plugin you are talking about is just in development and lt.rat said he will release it but nobody knows why.
private plugins are usually huge plugins which needed months for being created and not everybody likes to share such work without getting payed. there are other plugins which are very small but the idea is very nice so it makes your server to soemthing special -> more users connect to your server so it gets really popular. that is another reason for nto sharing a plugin.