The big idea is LESS important than good execution.
Most think that the big, NEVER BEFORE TRIED, idea is more important but there are lots of companies that do very well with good execution of fairly mundane things.
The only thing that is in infinite supply is ideas; There are probably more than 25 million smart Americans in their basements at any one time trying to come up with the next bid idea (like, say, Google). They are generating a huge volume of new ideas; that tends to suggest, in economic terms, a surplus of ideas while the skills to implement them are in much shorter supply and, hence, the latter will generally attract a higher price.
The market for new ideas, such as it is, tends to put a low price on them (just try to sell your BIG IDEA at a business model stage and you will see: a) how hard it is to do that and b) just how little you will get for it). Obviously, a startup that combines some type of innovation with good execution is better off than one with just sound execution.
http://www.dramatispersonae.org/UOttawaHomecomingSpeech16September2006_bilingual4.htm