Right; I forgot to mention. They're also (mostly?) available through the Sony bookstore, and IIRC through Fictionwise.com. They may be available in other ebook stores; Harlequin is promoting these widely.

But all those places have DRM, and the Mobi version from Harlequin will read on Kindles. (I forget that people with Kindles are not likely to care about DRM if they're downloading straight to the Kindle. I am probably less-than-rational on the subject of DRM.)