Any ebook you pay for at mobipocket.com has DRM.
In fact, with very few exceptions, MOBI ebooks you pay for at all sites have DRM. The exceptions are usually "multi-format" (buy once, download as many formats as you want). Multi-format ebooks never have DRM, because every DRM provider charges per format. Two major multi-format sites are FictionWise and
webscription.net which is primarily for Baen Books.