For my tests, I booted to Ubuntu 9.10 alpha 5 and installed Pidgin (version 2.6.2) from the Ubuntu repositories. Empathy, of course, was installed by default, with version 188.8.131.52 as the current build.
Although it's still possible that there will be minor changes to the two applications before Karmic's final release, the feature sets available in the alpha build likely represent everything users can expect in October.
ProtocolsFirst, a look at the protocols supported by the two chat clients:
|Skype (via plugin)||X|
Empathy lacks support for a few protocols, but the most widely used ones are well supported by both applications--which is no surprise, since they each rely on libpurple as their backend.
FeaturesHere's how Pidgin and Empathy compare on features:
Overall, the list suggests that Pidgin and Empathy are not that different when it comes to delivering core functionality. Admittedly, I included only features that I deemed important in the table above; Pidgin's extensive plugins offer a wealth of bells and whistles, like "Contact Availability Prediction," that might be fun but not essential for most people, and which are currently unavailable in Empathy.
Pidgin lacks working video-chat support (in principle it can be enabled, but I've yet to hear of anyone besides the developers who's managed to use it), but it offers a couple of other important features that Empathy still lacks. Ideally, all of these features would be implemented in both clients, but until then, this sounds like an equitable trade off.
To reiterate an assertion I made a couple of weeks ago when first writing about the Empathy/Pidgin controversy in Ubuntu 9.10, the overwhelming similarity between the two clients proves that this should be a non-issue. At this point, the Ubuntu developers might as well stick with Empathy, since it's already made it through the alpha releases, and focus their energies on more pressing concerns.