I predict it'll be available the same time the BL-6C cover comes out.
I've been here in HK two days now, and there are electronic shops everywhere (guys, it's a cellphone nerd's heaven). The E50 is always missing from the shops, it's not a big seller or available (but the others are, E/N series even that N71 that doesn't sell that well). The Nokia store of course has it, but not the 100 billion aftermarket joints. (oh yeah, and the AD-15 adapter is nowhere to be found, even at the Nokia store.)
It makes me wonder if Nokia has somehow limited the production run(s) of the E50, not thinking that anyone would want to buy it or something. The average electronics store will have 200 phones, so I'm not talking a by chance thing here -- I keep an eye out for it (so I can judge if the shop is cheap or expensive ).