Though the current General Conference is available through the official LDS scriptures app for iPhone and iPad, you could use an app like Stanza to read older General Conferences converted to ePUB in Calibre and read them on iPhone/iPad/iPod Touch, as well as any of the many other ePUB compatible PDA’s, smartphones, etc.
Update: I found out that the Android app Aldiko can read ePUB format. So all you’ll need to do is put this on your phone in the eBooks/import/ folder (once Aldiko is installed), then from the home screen of the app, hit your menu button, then the import option. You have to select “okay”/”import” once or twice, then it will make any ePUB books in that folder available for you to read on your Android phone or other device.
Let us know if you’ve converted, or know of any site that offer various LDS literature in any of the various eBook formats.