Hi, after trying to be able to read .mobi files on my new Android 2.2 Desire HD, I've worked out the following:
Amazon Kindle will list and open the .mobi files placed directly in the root of Kindle. It won't search or open titles in subfolders or your My Documents directory.
File browsing software won't open the files.
HTC's Reader (My Books) won't see the files, nor will Aldiko.
It's great that I've worked out a way to read them but it is a huge annoyance that the files have to be in the root directory directly as I've copied thousands of files sorted into directories - \Author\Title - but to read them on my Android I have to pull them all out jumbled up into the root directory with no sorting, catalogueing or anything.
But at least I can read them now.