Definitely not under 25. I've built startups for many people over the years (both as full time as a consultant/contractor), and at this point look at work on someone else's idea as dollars first, equity is gravy. Why? Early engineers take a hit on salary and any equity stake is quickly diluted. It is pretty common for engineers post series-A to potentially end up with a higher equity stake than someone that came in after seed funding when you factor in dilution. This is common.
These days I look at startups as an opportunity to have a significant impact, build something interesting, but what am I giving up for the particular company? Can I gain the same benefits through other channels?
I recall a YC event where companies were pitching looking for talent. At least the Justin.TV guy was honest and said "we work our asses off", the startup that pitched "we work together, we play together, and we hang out with our customers at 9pm trouble shooting" -- great if you just moved to the area and don't have other outlets.
I've had some grate discussions with a few YC companies recruiting, some were wrong fit, some wrong match, some wrong time. In general, positive.
But the original thread is right...for a lot of the talent some companies want, compensation needs to match the talent level desired and equity/option, that crap shoot needs revamping.