The problem comes apparently from the Touch-Mania repository and is described here (in German only, sorry).
Following their steps did indeed correct the problem I had.
So I’ll give you the translation:
- Connect to your iPhone with WinSCP / Cyberduck
- Go to the /private/etc/apt/sources.list.d directory and delete the file touch-mania.com.list
- Or connect via SSH and type the following: rm -rf /private/etc/apt/sources.list.d/touch-mania.com.list
This should make Cydia start again.
You’ll probably have to reinstall the Touch-Mania repository:
- In Cydia click on search, and select for “Touch-Mania”
- Click on Modify and then Reinstall
That did it for my iPhone…