Oh, now, I really do like this.
I've been muttering about this kind of thing for years but my crazy random outbursts are scattered around various posts and not in any kind of order like this.
I really like some of the ideas about changes to the Properties Palette (Window Properties in the presentation). This palette has way too much empty/unused space and even before 1.5 it was becoming unwieldy to use. With the extra functions in 1.5 - I especially notice it on OSX - there are so many sub-sub-scroll-lists/areas that it's very difficult to know exactly where you are without a good deal of thought. (See the attached screenshot for one example of the confusion. Notice the two scrollbars together on the right.) I do realise that 1.5 is still in development and things will get moved around, but this is the perfect time to see what can be done.
I particularly like the suggestion to convert the Properties tabs to side-icons (or even top-icons like GIMP). The existing tabs take up way too much space at the moment, so moving them to the side (or top) will free up a lot of extra "real estate".
Also, the different icons look great. Some kind of collaboration between Martin and otx (see the link from Kunda above) would do good things in my opinion.
Using an extra context-sensitive toolbar to offer some of the adjustments - like Inkscape, as mentioned in the presentation - Window Main (Tools) - instead of elsewhere looks very nice too. Anything to make the interface clearer and easier to use.
If I could add one extra thing, the Shape and Group tabs of the Properties Palette have much the same effects but on different things (with a couple of exceptions). Could they not be combined and made context sensitive? I.e. If you've got a group selected it offers group-related effects, or shape-related effects when the object selected isn't a group. It's just a thought.
I'll need to have a look at the presentation again but this could be a very good and much-needed step in the right direction.
A really great start Martin.