I was reading an article today on ign.com about this subject and I think it would be a good idea if Apple does it the right way, meaning...keep the price of the console affordable, make sure it's reliable, have some really kick ass exclusive games ready to go at launch and establish some top tier exclusive franchises, appeal to every genre of gaming, (this means don't just release these shitty shovelware and casual games like Nintendo and almost totally ignore the true gamers who got them to where they are now), make sure it has good online capabilities.
Apple already has a lot going for them now, they own the direct downloading market, they make some of the most innovative products around, they have strong brand recognition, and most importantly they have deep pockets to absorb the initial losses that almost any new console will face at launch. Yes, I think they should release a console if they do it properly!