Er, no, if the camera does a simple format that just rewrites the "table/index" (in Windows, NTFS and FAT, this table is called the MFT or master-file-table) of that particular filesystem to say that all of the sectors in the filesystem are free, the files are still recoverable. The nasty bit is that you have to go through all of the space in the entire filesystem, sector-by-sector to find the data that was there before. Most cameras do this, because it is much faster, both to their cards and internal memory.
If you do what is called a "low-level format", then the data is essentally gone, because the OS goes through every sector and verifies that it's functional, and then wipes it. Unless you have some SERIOUS recovery software, and technical know-how (and in the case of magnetic drives, and electron microscope and lots of time) you can pretty much forget about recovering your data.