Not really. Most raw formats are
stored in a TIFF-EP format, but the data itself is proprietary to the camera and hardly universal. The reason so many programs support so many formats can largely be credited to Dave Coffin, who wrote and maintains the freeware DCRaw application, which supports a vast array of raw formats.
DCRaw can do this because all it does is decode the raw files, it doesn't have much in the way of image manipulation features, and doesn't have a commercial user-base to support. He also adds cameras incrementally as they appear.
The situation is quite different for an application like Aperture, ACR, C1Pro - these have to keep many many other features supported, and they need to maintain a
consistent output range for supported cameras and filetypes. As a consequence they do a lot of processing to the files that DCRaw doesn't do - even if they use dcraw internals (ACR at least used to, dunno if it still does)
iView, GraphicConverter, and apps of their ilk generally don't have their own raw routines at all, they rely on dcraw directly, or on manufacturer-supplied sdk "black box" code. As such, the support in these apps tends to be extremely primitive. In iView's case it often doesn't even decode the raw file at all, it will just pull the embedded preview out for display purposes. (Which is a very, very smart thing to do for a catalog app, but not a good conversion plan, since it isn't actually converting anything.)
The upshot is that sophisticated decoding routines do in fact take development resources. There will
always be some camera that some person has which is off the radar of any given developer. That's where DNG is so important - Adobe is taking pains to support as many formats as humanly possible - it just makes sense for Apple and others to leverage this support and free up resources in-house to focus on critical features of their program. (Wouldn't you rather see Apple fix, say, the layout tools, or noise reduction, or layered file support, or the metadata bugs, or ... instead of adding support for a camera you don't own and can no longer obtain? I sure would.)