Google's search engine algorithm is a really extraordinary piece of software - it goes through millions of websites and then takes hundreds of factors into consideration so that it can rank them in terms of importance, relevance and quality for every possible search term. Of course, something like this is going to be constantly updated so that it can accommodate new things in the ever-changing world of the internet and so that it can consistently bring a better experience for users. The Penguin update is the latest addition to the algorithm and something website owners have been thinking about and waiting for for a long time.
This change happened only a few days ago and could have a big impact on a variety of websites. Maybe your site will start to rank more highly or maybe your site will drop significantly - either way, this could potentially have a huge impact on your business! Equally, it's possible that your won't experience any impact at all. There are several things which might factor in: if you've been doing any kind of dubious SEO tactics to make yourself rank more highly, then as Google updates, they're more and more likely to figure out what you've been doing. On the other hand, perhaps their updated algorithm will look more closely at all the good work that you've done and you may see yourself begin to rank more highly! It will take a few weeks for the effects of this change to be fully felt (obviously, there are millions of results which need to go through the new algorithm, which will take time.)
Hopefully this change will either not effect you in any way, or it will give you a positive boost. It would be a huge shame for your business to suffer because of changes to a search engine that is nothing to do with you. Time will tell and if you do go down in the rankings, perhaps this will give you a good idea of how to improve your site. Whatever happens, I wish you continued success with your eCommerce website.