This may be the best news i've heard all month! Possibly even all year so far.
I've complained repeatedly that although i really appreciate GOG's stance towards DRM in the long run, in the short run i'm too easily seduced by the convenience of the Steam launcher in general and the compulsion of achievements and tracking time in games in particular.
That's sometimes led to me buying games on both Steam and GOG, but more often it's led to me buying games on Steam and just not bothering on GOG. Knowing that tendency on my part i've often said that GOG would get a lot more of my business if they just implemented an optional launcher that provided the same benefits as the Steam launcher. I would then always clarify that such a launcher should be optional and we should still have the ability to download games and install them without it, but that i'd jump on the launcher bandwagon as soon as it was available.
I guess i wasn't the only one saying that, and assuming it's everything they're promising it's now time for me to start putting my money where my mouth is :)