Ask Early, Ask Often: "How do you see the authorship on this?"

The essential currency of the modern biomedical science career is the research publication. By which I mean your name listed as an author on a peer-reviewed journal article. This has always been the case and is not selective to science, the publish-or-perish mantra is common to many academic disciplines.
Nevertheless. In bioscience the current realities of career, funding and advancement put a huge pressure on scientists to accumulate as many authorship credits as possible.
Which means you must ignore conventional or traditional concepts of how things are done, what is polite behavior, whether you are being a selfish snot, etc and discuss authorship early, often and continually with your labmates, mentors, collaborators and trainees.

Nevada Loves the Vicodin, Delaware Prefers OxyContin

Recreational use and abuse of prescription narcotics has received much attention in recent years, from the 2003 revelation that Rush Limbaugh was abusing OxyContin to the multi-drug overdose of Heath Ledger. If you do a little searching you will no doubt run across some descriptions of prescription narcotic abuse as growing and alarming trends. Kevin Z of Deep Sea News and The Other 95% pointed me to a handy little tool to take a look at a couple of aspects of these trends.