I have noticed that when I move apps to the SD card, it doesn't move everything. Is this a bug or a known behaviour or something weird going on with my phone?

Here's an example:

• Start point: Phone free space: 18MB
• Install Skype app: Phone free space: 3MB, Skype is apparently using 15MB for the App
• Move Skype to SD Card: Phone free space: 8MB, Skype is now apparently using just 5MB for the App.

What appears to have happened is it's only moved some of the App, not the whole thing. It's a real pain for me as I have an HTC Desire, which doesn't have much internal memory (I live on the balance of the low memory warning). It's running the official HTC Gingerbread install...