Sure, Swing is still used in older projects and is still supported by Oracle (meaning that they still ship it with the JRE and they will for a long time), but afaik, they don't put any effort into it any longer, e.g. no bug fixes or new controls etc...
I can't find any official statement about it, too, but maybe I've read something like this in a mailing list or it's just my (or general) perception.
It's similar to other technologies which are supported/used but considered dead nonetheless, like Flash or Sliverlight, which make those technologies unattractive for developers.
I wanted to say it's probably one of the reasons (or even THE main reason), why development on Spark has decreased.
And I also agree with wroot about video/voice chat. It's probably to complex to have those things implemented in a non-prototypical, usable way in the near future, even if there were a few developers.
Btw.: Does anybody know the history of Spark development? Was it developed by Jive and then opensourced?