This is applicable to the Notes and Administrator clients too, but I only get to pick one IdeaSpace. :(
As a 'relatively' new entrant to Notes design and administration (I've only been doing it for a few years off and on), I'm incredibly frustrated by the poor learning materials for new developers. Coming from the Linux/OpenSource community I am consistently drawn to PHP/AJAX/MySQL solutions because there is far more competent learning materials all over the web, available on Amazon.com, and on the bookshelves at Borders, etc.
While the blogosphere is rich with ND grey-beards who know the system inside and out, the knowledge is dispersed and touching one nugget or another, with little big-picture vision tying it all together. Redbooks CAN be useful, but are again, addressing only one piece of the puzzle, and are often terse, turgid tomes which are dizzyingly complex in explanation, and often give code examples which aren't particularly useful enough that developers (speaking for myself, of course) would care to implement or build off of them.
The help files are useful as a reference, but don't provide much assistance, or a followable narrative about the platform. It's cross-referencibility combined with it's lack of bookmarkability or tabbed interface make it impossible to define a recommended sequence of learning to maximize understanding and productivity. Barring about three books, the content in the off-the-shelfer's are ~10 years old, often repeat themselves, and limit themselves to the same scope of development examples. How about a chapter on "how do I develop W3C valid xHTML & CSS - based Domino applications?" Or, "how do I build apps where activity in one frame update the contents of another using only NATIVE code (ie no composite apps frameworks)?" I know there is an article here and there that touch on these, but there's no way to trace the necessary skills back down the chain to see what I need to know how to do in order to make sense of the tutorial I want to implement.
As a solution, I think it would be really cool to have an IBM sponsored (or if not, so be it) educational wiki where dynamic educational resources can be published, commented on, edited (by users with the appropriate privliges), and cross-referenced. Ideally, it would be an NSF which could be viewed on the web, as a locally replicateable client app, or shoved in the new sidebar. Not only would it be a great place to have a constantly evolving Notes/Domino educational system, but it would be a place for ND gurus to share their knowledge which can bring traffic back to their site, allow people to note where there are implementation bugs, discrepencies, or misconceptions, and it also can grow the developer base.
Tutorials could be indexed in such a way that there would be an "official" learning order, comments, alterations, and offshoots could be marked as supplementary, and periodically, the "official" narrative could be released as a digest, or a printable book, or some such thing.
I also think it'd be cool to train content creators using the "Head First" style of authoring. Those books have allowed me to start using all kinds of technologies within a week or two because of how simple it is to absorb the material.