And if you are lucky, Amazon will even be able to convert them.

About week ago I wanted to test it, I tried it with bunch of epubs from various sources and only about half converted successfully.

Yeah I often have issues with "fancy quotes" not getting converted correctly if I email an ePub to Kindle. They get converted to HTML entities :(

With Calibre it works but it's an annoying extra step. I hope Amazon fix this issue before they officially start supporting ePub.

Try using epubcheck on those to see where the finger really should be pointed.

There are a lot of really crap "epubs" out there.

https://www.w3.org/publishing/epubcheck/

There's no magic ASIC on the Kobo that transfers the stream of bytes into the stream of pixels; ePub support is in the Kobo software. Amazon now has this support in their software. The fact that the conversion software runs on Kindle servers (and not on the Kindle device) is insignificant to me - what's important is I can have an ePub and can read it on the Kindle.

Not sure what to make of this post. You know that you can drop files straight to your Kindle through a USB cable, right? As long as an epub loaded this way doesn't work I can't see how you can say Kindles support epub.

Yes, you can use Amazon's weird conversion service to convert them, but you could do that with Calibre (or just pandoc) anyways, and probably with less friction too.

So long as the server doing that continues to exist.

You have a point. OTOH, my three Sony readers and my Nook supported ePub without any servers, but all are dead now. And again, without that server it's just back to Calibre.