One interesting highlight of this release will be: Notifications.
Publish::Speech speaks the feed content to the audio (I was trying to save it as WAV but I couldn't get any luck with SAPI4 ... Help wanted), Publish::MSAgent uses Microsoft Agent to speak it up with animation (screenshot), and Publish::Grow sends notification to Mac OSX Growl (screenshot).
There's also a hack to print the feed (automatically!), and I created Publish::PDF inspired by that. Right now it uses Audrey's PDF::FromHTML module and it doesn't look most beautiful. There should be a better way to create more neat PDF using other software on Windows / Mac OSX platforms.
That's the main updates for 0.5.4 (which also contains a neat filter plugins by tokuhirom), and I plan to have a little bigger revamp in the next release: CustomFeed reorganization and Cache mechanism.
In addition, there've been already a couple of plugins that are waiting to be included in the next release: Publish::Pipe, Filter::StripImage, Widget::MM, Publish::Feed and Filter::HatenaDiaryKeywordLink.