Wallaby isn't the same thing, is it? I just looked it up (and I don't know Flash, so correct me if I'm wrong) but from Adobe's website[1], Wallaby works on FLA files and Swiffy works on SWF files, the key difference being FLA is the working, editable animation file format and SWF is intended to be a non-editable 'production' format. Thus, Wallaby is useless if I'm looking at somebody else's website with an SWF file on it (I figure going from SWF to FLA is probably analogous to decompiling binaries to source code?).
Swiffy works well if you want to convert someone else's Flash content, while Wallaby is good for developers to convert their own content and then add any additional functionality that is missing from the conversion. As Swiffy's output isn't easy to read or edit.
1. http://labs.adobe.com/technologies/wallaby/