The final output is XHTML 1.0 Strict with the layout done with CSS - seemingly inline CSS with a huge stylesheet embedded in the head section of each page, unless I'm missing a control which allows for an external stylesheet. The headings etc. use semantically-rich
h2, etc. elements. The end result is certainly a cut above many Google pages, and similar in approach to the kind of markup seem with blogger, however unless the styles can be shared across many pages the page weight is a concern, and the content is pushed a long way down the page.
For the publishing interface itself, my first reactions are not all positive. There are some bugs, which is a given due to the fact that it is (another!) beta - the "Image" button is non-functional, for example. The look is clean and simple and the controls are clear.
At a first glance (I haven't done a full evaluation), Google has learned nothing from this experience. There is still not a single clickable standard anchor link on the page. Even the Google logo and "My Account", "Help" and "Sign out" links are standard text with onclick events - "fake" links styled as anchors. No accessibility aid will be able to find these links. There is seemingly some attempt at keyboard navigation, but when you tab to, say, the Heading button, pressing Enter on the keyboard has no effect whatsoever (no onkeypress function, I assume).
The solution to Gmail was that Google were pushed into providing an alternative interface which had better accessibility. It is a huge shame that caring for users who don't or can't use a mouse or who don't have two functioning eyes doesn't appear to be particularly important part of Google's philosophy. The criticism about Google using CAPTCHA images [webmasterworld.com] is sadly the tip of the iceberg.