Following my recent post on the development of Flash website crawling by Google, there is now sufficient information to answer the issue of the SEO impact of this new ability. It is becoming clear that sites built in Flash are still not good for the Search Engine optimisation of your website.

There are a number of reasons for this:

1. Google is the only search engine that can currently crawl Flash websites - and although Google accounts for around 87% of search traffic - the other engines, such as Yahoo and MSN can still help you drive traffic to your site, so you should not build your website to please Google alone.
2. Many Flash based websites only use one address without any subpages so only the one URL can be crawled by Google. For example a non Flash site will have a home page of www.yourcompany.com and sub pages will have their own addresses such as www.yourcompany.com/products but if the website were to be loaded in a single Flash file the URL would remain www.yourcompany.com even when a visitor is on the products page. Therefore, the sub pages like this product page will not be crawled by Google.
3. If the Flash file is loaded using JavaScript the site won't be seen at all as Google can't read many kinds of JavaScript
4. If the Flash file on your site dynamically loads other resources - such as HTML or XML these won't be indexed as the dynamic load makes Google behave as if they are part of the main Flash file and not separate.
5. As with non Flash websites, the Google crawlers cannot read images and so any images with text on them, such as buttons or promotional boxes won't be classed as indexable content - meaning the value of your site is lost to Google.

The functionality of the Flash Crawl tool is still in it's infancy and many of these issues may well be resolved in the coming months but in summary, avoid Flash on your website if you want the site to perform well in search engines.