For heavy users of the built-in iOS Notes app, there are already some different ways to share notes. Besides using cut and paste to transfer notes to another app, tapping the share button provides two options for direct sharing: Messages and Mail. The jailbreak tweak ShareNotes changes all this, providing two additional ways to send iOS Notes directly to social media.
Installing ShareNotes from Cydia will add Facebook and Twitter buttons to the share function of the Notes app. Tapping the appropriate button will create a message from your note text, just like sharing to these places with any other app.
Although this tweak is useful for those who like to compose text in the Notes app and have something to share, there's no built-in way send notes longer than 140 characters to Twitter. Keep this in mind before you try to tweet using ShareNotes.
ShareNotes is available on Cydia from the BigBoss repo free of charge. Check here for instructions on how to jailbreak iOS 6.x with evasi0n. You can also find out how to purchase and install Cydia tweaks with this guide.