Pownce released last night the first alpha of their new desktop client. The previous, at least for me, had become unusable due to login problem and such, so I'm quite happy that there is finally an official -- yet still alpha -- replacement.
This new version thankfully comes with a simplified style and also embeds content like YouTube movies and the like instead of requiring users to once again go to the actual website. The client still uses Adobe AIR and is therefor available on Windows, MacOSX and Linux.