The Ubuntu Professional Certification

Says you need LPI under your belt already to pass, I recommend LPI Linux Certification in a Nutshell by Steven Pritchard

Unix Review > Certification: Exploring the Ubuntu Professional Certification

To become certified as a Ubuntu Professional, it is necessary to first become Level I certified by LPI (LPIC-1), which requires passing two exams on vendor-neutral Linux topics. Following that, you must pass one more exam ($150) specific to Ubuntu. At this time, the exact number of questions that will be on that exam, and the length of time allotted for it, are unknown but it is expected it will mirror the two Level 1 LPI exams (~60 questions in 90 minutes).