Damn it... Since the Activision announcement I was hoping their next big thing would be a deal with EA to get the Origin catalog here... :(
And no, it's not Planescape Torment... they would make a lot more noise...

Two new publisher deals?

Two new deals sounds great!

Heavy artillery, heh? :)
If Eidos isn't one of these publishers... then hurry up please - I really need yet another copy of every Legacy of Kain title ;).

Yep that must be it, or maybe they managed to secure another batch of titles from Ubisoft.

You guys are weird. Weekend deals are always announced on THE WEEKEND. :P
They've mentioned an announcement coming Thursday. Announcement x deal = new publisher deal(s)

It's ambiguous term. It can mean a sale, but it can mean a new publisher deal. Or both :P.
Anyway, from a not so old interview:
"The next big thing for us will happen at the end of March. We are finalizing another major deal that will boost GOG's catalogue with some of the most-awaited games from the top of our most-wanted list. We will gladly tell you more about it in March :)".

And they'll gladly tease until the time they announce it...

Yay! Double awesomeness, tomorrow. :)
Since he said "new deals", I guess it doesn't count the publishers which are already here, like ubi. And it isn't discounts, but new contracts for publishers/series/etc.
(That's correct if we are talking about publishers... otherwise GOG will surprise me if it is a publisher + something else.)
The "twitter teasing guy" should clarify this. :p

Then the teasing wouldn't be as effective :P.

That's the intention.
Why wait till tomorrow if he can deliver the news, right NAO. :p

Hmm, very interesting. A completely different approach this time from GOG. Unlike last time, where it was hyped beyond belief, the proverbial cat was deliberately let out of the proverbial bag long in advance, and only a few particularly silly or thick-skinned people failed to see the truth, this time it is almost incidental. This probably means one or more of a few things:
a) Last time it got blown out of proportion to a far greater degree than GOG wanted it to be (possible)
b)It's not as big an announcement as last time (Depends. Individual opinion when we know what the announcement is. For example, if the announcement are that Atari and Eidos are joining the service, then some might consider one of them to be a bigger deal than Activision, or together to be a bigger deal, or completely insignificant.)
c) For reasons best known to themselves, GOG wish to keep it a complete secret beyond the fact that they have an annoucement. (Makes sense to an extent, since this double-whammy anouncement is coinciding with a CDP conference on Thurs, where GOG get about 20 mins to speak.)
Irregardless, interesting times.

Or they are trying to put the spotlight on the Witcher 2.

spuare-enix and eidos.