Originally Posted by rwhe
Books: EPUB, PDF and MOBI
Images: JPEG, GIF, PNG and TIFF
Text: TXT, HTML, XHTML, and RTF
Comic Books: CBZ and CBR
So MOBIs are officially supported, and they do work sometimes. But they've usually given me headaches on my Glo and my old Touch...
By the way, ironflute, I do think this is disingenuous on Kobo's part, even borderline deceptive. I'm pretty sure they know their MOBI rendering engine is flaky at best. One of the reasons I bought my Touch oh so long ago was that I could apparently dump almost any file format onto it and just read it, according to the ads. So if you feel cheated, I feel your pain.
But converting MOBIs to EPUBs is extremely easy with calibre, and Kobo's support for EPUBs is of course very good.
I recommend opening your Kobo's disk on your PC, sorting your ebooks by filetype, and mercilessly deleting any "forbidden" files.
Don't throw away your nice new Glo yet!