CopierciN is the name of a new application that has been released in Cydia. The application allows you to copy/paste text to SMS, Notes, Mail applications and files in the filesystem.

CopierciN is currently in beta with a lot of known issues. It might cause some problems like corrupting files as it modifies two system files (notes.db and com.apple.mobileSMS.plist file), so before using this app a backup would be advised. CopierciN is available in Cydia under BigBoss repository, in the Utilities section.
More info on how it works: CopierciN