I have known one Ph.D student (who spent 3 months in our lab as an exchange student) who had one person doing his prep-HPLC (me, sucker that I was), someone else doing his mass spec, someone else doing NMR, and so on. He then collated all the data and wrote it up it as his own. When we pulled him (and his supervisor) up, they were both adamant that it was acceptable for a student to receieve "help" of this nature, and that as it was for a thesis, not a paper, he did not have to acknowledge other labs I'm not sure if that's true, but it's certainly unethical.
Most people I know have had analyses done by someone else (usually because the instruments were not working in their own department) but they always acknowledge that in their final thesis.