If you're not registered there, go ahead and comment here. I'll read it. So far the only person who's looked over anything has been me, so I need opinions from a wider audience to be sure I'm not missing the forest for the trees.
Here's the thread.
Here's the compendium post with all of the information for the Heroic Tier. This is probably the more important thing to go read. Its the only post that's updated for balance- the earlier posts that cover the same information aren't necessarily balanced right. This isn't either, of course, but that's what I want comments for.
It hasn't got any flavor text written out yet other than one line descriptions of some of the powers.
The flavour is great. I think the shadowcaster should be a controller too but I think all controllers will be built the same (i.e. 10 hp at level 1 and 4 per level). I think that shadowcasters should have abilities that mitigate against the fact that they have to get up close to use many of their powers in spite of their poor armour and low hp.
Caul of shadows could be a class feature to add +1 AC and would function like the sword mages extra armour, a few powers to gain temporary hp could offset low controller hp, and powers to gain combat advantage via stealth.
It's a bit too late at night to do a proper review but Flicker stands out as an attack power with no associated attack. It should be a Utility and might even be powerful enough in 4e to warrant it being even higher. I haven't checked out higher level teleport effects yet but the sustain power seems too awesome. You could allow teleport in, attack, and teleport out again (which is what we used Flicker for anyway) but probably limiting this movement to a more limited 3 squares with no sustain. There might be some teleport attacking powers for the swordmage to compare with.
You might need to spread the existing 3e shadowcaster powers more thinly as we have 10 extra levels to cover in 4e. This could also be a way of limiting the mastery bonuses until higher levels. There was also an online WotC article with a few new 'urban' paths that might help pad things out.
I think low-light vision should be a level 2 utility with sustain minor rather than a class feature possibly attainable permanently with a paragon feat. Darkvision should be a higher level daily power.
Noctumancers counterspelling could be a good base for higher level powers too, gaining various secondary effects which last until the end of the next round.
Somebody did post the beginnings of a shadowcaster thread in the house rules forum here. It was in its early stages and bears some similarities but you might find it useful to compare the notes. I think that sustaining shadow was proposed as a class feature possibly something that could advance at each tier or be built upon with tier appropriate feats.
Just my thoughts! Nice job!