The Comma Operator's Deprecation Can't Come Soon Enough

[Meta via Digitalmars-d]

On Wednesday, 23 July 2014 at 19:04:52 UTC, Ali Çehreli wrote:
> Reminds me... Is everybody aware of D's for syntax?
>
> import std.stdio;
>
> void main()
> {
>     for ( {
>             int i = 42;
>             double d = 1.5;
>             string s = "hello";
>         } i < 100; i *= 2) {
>
>         writefln("In the loop with %s %s %s", i, d, s);
>     }
> }
>
> :)
>
> Also note the absence of ; before the loop condition.
>
> Ali

What in the hell is this? Is the { int i = 42; ... } block 
counted as a lambda or a scope? In that case, why is i still 
available outside the block in the `i < 100; i *= 2` expressions? 
I feel like my whole world has been turned upside down.