I'm creating now client with Qt4, have tried Qt5 on qtonpi, but it is not usable at the moment(didn't tried Qt5 on raspbian yet, but don't think it is better there). At the moment it is an alpha version with simple gui and only chat facilities(with contacts list and so on). Gui is scaled, so you can use it as simple desktop application or fullscreen app with big fonts and icons to be used on TV. App will provide some kind of RPC communication(REST + JSON/Simple XML/Plain text +KeepAlive) to control it over the network. Android remote control app is also planned.
I hope I'll get time to release first beta version this week for testing purpose...
A SkypePi would be the perfect size to turn any tv into a Skype-enabled monitor (minus the camera).
Why "minus camera"? camera and audio is also planned...
I think the way to go would be to make some sort of skype daemon (here I'm thinking of some sort of mpd style application)
something smart enough to run alone as a proper skypeclient being controlled from the command line but which at the same time would allow relatively easily to code your custom GUI over it in basically whatever language you'd like.
SkypeKit is actually a daemon and you can code your client in many languages... Building daemon for daemon will be just waste of RPi resources and how do you imagine support for many languages? Plugin system with language interpreters for RPi? I don't think this will work well and smooth enough... And what about Video Calls? How do you imagine transition of video streams to plugins?
I don't see reasonable opportunity to develop such kind of M$ like mashups for device with 192MB RAM, 700Mhz CPU and ~700 bogos...
Using Qt5(when it will get stable and usable release) we can use QML for GUI, so it will be pretty customizable.
For WebApps and custom small apps or plugins(like plugin for xbmc) RPC protocol to control main client, read contact list with statuses and possibility to send chat messages will be enough for most of real world use cases, and it is planned.
Of course it is all IMHO