The misdemeanor convictions likely won't hurt your career, but depending on the nature of the felony you might have a hard time. For example, I've seen a felon with a computer fraud and abuse conviction get all kinds of great job offers. Conversely, at my company we tried to hire someone who had been convicted of murder and served his time, figuring he'd paid his debt to society and that this was now irrelevant, but our hiring decision was overruled by the legal department. Finally, there may be specific felony convictions that prohibit certain job functions. E.g., if you've been convicted of any kind of embezzlement, you may be barred from jobs that involve managing government grants. Sex crimes obviously carry a huge stigma. And though the drug laws are a bit out of control, I'm not sure how bad drug convictions, at least if you aren't working with kids. My company is required by federal law to be a "drug free workplace," which forces us to sign documents, but the content of those documents isn't as restrictive as you might think--basically we have to agree not to use, possess, or distribute drugs at/during work, but what we do on our own time off company property is our own business. A past drug conviction wouldn't be a problem.

Well, Scott Aaronson has written: "If Vinay Deolalikar is awarded the $1,000,000 Clay Millennium Prize for his proof of PNP, then I, Scott Aaronson, will personally supplement his prize by the amount of $200,000.

"I’m dead serious—and I can afford it about as well as you’d think I can." See his blog.