When will release the next version of songbird?

When its ready I assume..

Never trust a company who tell you exact dates. Even Microsoft never announces a release date until the CD's are being manufactured. Because if the developers find a serious bug the day before release, they would get harassed if they delay by a day or so to fix it.

But I'd expect soon. 1.4.0 in the repos isn't changing that often. However, there may be documentation still to do, etc. Your current version of Songbird will offer the new version when its available to install anyway ;)

Or you can use the copy in the developer repos (which may or may not be final, but probably very close).