There are some good examples in this slide deck, but it seems to be lacking a deeper explanation of "why" the author came to each conclusion.

There is a reason companies choose abstract words for their products. If the Wii was still "Nintendo Revolution", it would quickly become un-revolutionary. If Twitter was called "Status" or "Update", they would be narrowly defining their intent for the product. Abstract names don't carry the baggage of a definition.

As an aside: I am coming to hate these slide decks filled with one-liners and little context. Why can't we get a transcript of what the speaker was saying for each slide?

You sure can. But I have to go write that up too.

The Why was explained in the talk itself , naturally. The video will be posted

destraynor, thanks for the presentation, a lot of good thinking there. Subtle differences between "verbs" and "nouns" of interfaces and cultures they create inside social networking services is one of the reasons that I don't believe in the idea of federated social networks, i.e. sharing superficially similar content "nouns" and "verbs" between social networks.

Waiting for the video of the talk!

I hated when Gmail changed "Older" and "Newer" in favor of "<" and ">".

It wasn't "Previous" and "Next", since it wasn't clear, but with the UI redesign they skipped that consideration.

Also I hate the "go back to inbox" button that looks exactly like a reply arrow

Yeah, that's a good example.

The orientation of left and right for older/newer can also be weird

Be sure to click through the slides. The blog post may not be overwhelmingly useful, but the presentation has plenty of helpful examples of interface copywriting done right (and wrong, too).

Don't forget proper spelling and grammar. Poor spelling and grammar risk derailing your reader's train of thought.

I actually like the idea of a Dribbble for copywriting a lot!