The tweet in question from today:
35% Off Sale at http://t.co/IN8fP8dSHb - http://t.co/jnlivwg6Lz
— SLGPublishing (@SLGPublishing) June 9, 2014
If you go to their website, it's not even mentioned at all. The site itself is extremely basic, stripped down from the last time I visited, which I admit was awhile go. A casual glance might not even give an indication that they are still actively publishing, as the "news" at the top is now nearly a year old.
There's no way to tell if the sale is only on physical books or also includes their digital line, which I definitely recommend. Among the physical books listed, you can't go wrong with early Faith Erin Hicks (Zombies Calling) or the first book in Andi Watson's Skeleton Key series. There is also Samurai Jam by Watson, as well as Derf's The City.
The link from the tweet states as part of the sale text, "Too Stupid to Quit, Too Mean to Die" which indicates there may be some problems with sustainability. I remember a failed Kickstarter to revitalize their space awhile back. The lack of website updates and the sparse look of their online presence (along with losing publishing rights to Pinocchio Vampire Slayer to Top Shelf) indicates there may be some serious issues going on.
That would be a shame because while I haven't been keeping up with SLG (I'm clearly part of the problem), I have enjoyed the books they put out in the past, especially in the digital line, where Sanctuary, Peabody and D'Gorath, and Monstrosis are all recommended.
If you've been looking to pick up some summer reading, definitely give this a look. SLG is an underrated publisher and I'd hate to seem them fold up shop. They've created too many good comics over the years.