The latest one is Hummingbird (they all have great names). This one is thought to look at the whole query from a user and its meaning rather than particular key words in a query. In that way Google may deliver better search results for their users.
How does this affect small business owners? If you do not do much SEO then you may not be taking much notice of where your website is ranking. Perhaps your website is to refer customers to rather than be found in Google.
If you do undertake SEO or have a SEO company which does this for you, then they should be able to explain whether this update affects you. Should your website be focussed solely on keywords and not valuable content, then you may have a problem. Ultimately, well written informative content will always be the best way to attract visitors to your website and keep them there.
It can be quite alarming to wake up one day and find that your website ranking has dropped, particularly if this is your only income stream i.e. you are an online retailer. Keeping your site optimised is always a good thing but your website should be natural, engaging and compelling for the visitor. Keeping these things in mind will avoid any surprises next time an update comes along.