PS Publishing, since the middle of june apparently. The title The Wurms of Blearmouth does little to explain the continued story from Lees of Laughter's End but the blurb is as wonderfully whimsical and with the comedic turn of phrase that you've come to expect from the novellas. I found it on the A Fantasy Reader blog, with cover pictures from PS Publishing as well.
While browsing my local sci-fi and fantasy bookstore to see if they had a pre order available I noticed that they have the first book in Erikson's Kharkanas trilogy available, and slotted for a july 31 release date. Forge of Darkness is a definite read on my 2012 radar.