“In addition to the new name, this release features extraordinary enhancements to features and functionality over the previous release.”

(pidgin.im)

According to moderators from the ubuntuforums Pidgin will be part of Feisty’s repository soon meaning we hopefully won’t have to wait for the next Ubuntu release in October to receive Pidgin as an update to Gaim.
For those being impatient, I can recommend ubuntu.schmitke-hb.de where you can already download Pidgin via schmitke’s repository.