Resumes - how long is too long?

I have been trying to put together my resume in order to start applying for jobs. I came across this post and it made me question what I should really put on it. I've always heard that your resume should only be one page in length, but I really feel that I have enough valuable experience to make mine longer. The PRChronicle post says that if you need to, do it. However, everything I have ever heard about resumes would say PRChronicle is dead wrong. Which is right? I hope it's the PRChronicle because I really need that extra room.

I have revamped my resume about 948384 times so far - have to make sure the wording is perfect and that it really shows just HOW MUCH I've done - especially in my last internship - phew I did a lot! But I feel like it is important to keep a little "in your pocket." as my class' recent guest speaker told us about giving good presentations. "Always keep some ideas in your pocket so you can pull them out if it feels right." I think that should apply to resumes, too - and, well, to life in general - you can't always put it all out there on the table. However, if I keep some of the good stuff - like my huge event planning experience - in my pocket, maybe they wont think I have enough experience to offer me an interview. It's all so confusing! Time for revamp number 948385!