On the subject of associating your iPhone app with file types.
In this informative question I learned that apps could be associated with custom URL protocols.
To deal with any type of files for my own APP, I use this configuration for CFBundleDocumentTypes:
CFBundleDocumentTypes
CFBundleTypeName
IPA
LSItemContentTypes
public.item
public.content
public.data
public.database
public.composite-content
public.contact
public.archive
public.url-name
public.text
public.plain-text
public.source-code
public.executable
public.script
public.shell-script
public.xml
public.symlink
org.gnu.gnu-zip-archve
org.gnu.gnu-tar-archive
public.image
public.movie
public.audiovisual-content
public.audio
public.directory
public.folder
com.apple.bundle
com.apple.package
com.apple.plugin
com.apple.application-bundle
com.pkware.zip-archive
public.filename-extension
public.mime-type
com.apple.ostype
com.apple.nspboard-typ
com.adobe.pdf
com.adobe.postscript
com.adobe.encapsulated-postscript
com.adobe.photoshop-image
com.adobe.illustrator.ai-image
com.compuserve.gif
com.microsoft.word.doc
com.microsoft.excel.xls
com.microsoft.powerpoint.ppt
com.microsoft.waveform-audio
com.microsoft.advanced-systems-format
com.microsoft.advanced-stream-redirector
com.microsoft.windows-media-wmv
com.microsoft.windows-media-wmp
com.microsoft.windows-media-wma
com.apple.keynote.key
com.apple.keynote.kth
com.truevision.tga-image
CFBundleTypeIconFiles
Icon-76@2x