okeanu, the coder who brought you CrystalTracker, has today released a new standalone Yahoo Y! Messenger client for BeOS, BeY!. Y! was already supported by the imkit, but the imkit seems to prefer running on BONE systems, and provides a less traditional interface - not that that is a bad thing.

BeY! uses NetPositive to provide some its interface, and the cross-platform libyahoo2 to manage the Y! protocol.

EDIT

It seems that BeY! also only runs on BONE systems. Thanks to slaad for pointing this out.