I’m not quite sure why this hasn’t been emailed to all existing owners, but the ebook of C# in Depth 2nd edition is now available in mobi and epub form, as well as PDF.
You can download it from the Manning user account site. You need to have the existing ebook first, but if you have the hard copy there should be a voucher in the front which will let you get the ebook for free. (This should work wherever you bought the hard copy from; it doesn’t matter whether you originally ordered it from Manning or not.) If you don’t already have a login for the user account site, just register using the same email address that the ebook was sent to. That way the system automatically credits you with all the ebooks you’ve bought. If you have had ebooks delivered to multiple email addresses, you can add those in the settings page.
Anyway, click on the link to C# in Depth, and you can download the book in any of the listed formats – if you want to use it on a Kindle, just download the mobi file, copy it to the Kindle and you should be well away.