GYach-E supports Voice Chat and Webcam for Yahoo! Messenger in Linux. It can be installed in most Linux distros by compilation from source. Visit the project homepage here.
Ubutnu users can install GYach-E by simply enabling repository and installing via Synaptic Package Manager.
Enabling the Repository:
Open up Synaptic Package manager. Click on Settings, Repositories.
Click on Third Party Updates tab and add the two lines one at a time according to the Ubuntu version you are using.
Refreshing the software list
Click on Reload in Synaptic and wait for the list update to complete.
Installing GYachE Improved
Search for gyachi in synaptic and mark for installation, apply.
Now, Launch Gyach-E from Internet menu and enjoy.