This is the most approaching clone of Google Reader I've seen so far.

It has one big problem, however:

A feed can have only one tag (or, if you see a tag as a folder, a feed can be only in one folder).

This is a big problem because Google Reader's UI encouraged to add multiple tags on a feed (you didn't moved a feed from one folder to an other : you selected a list of tags the feed appear in). And the OPML format allows this too.

So, if you import an OPML export, half your feeds may appear to be missing.

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An other great Google Reader alternative is http://yoleoreader.com/ . Apart from its UI sometimes freezing for a second (maybe due to synchronous I/O or too long script execution), it's an other great Google-Reader-like RSS reader.