I just checked that myself (it's a killer feature as far as I'm concerned and I want it too). It looks as if DW does support it, but only if you have a paid account.

Not surprisingly, since that's how it works on LiveJournal, too, TTBOMK.

I've had a paid/permanent account over there for so long that there quite possibly several features I use without realising they're not available to non-paid accounts.