Adobe's Flash plugin has up until recently been once of the most popular ways of displaying dynamic content on websites. Whether you are looking to have a background image for your website that moves and blends, or a navigation menu that transitions beautifully when you hover over an item, Flash is a great piece of software. Recent developments in the computer industry, however, have put Flash's future in jeopardy.
As a web designer and developer I will first and foremost argue that regardless of Flash's future availability. core features of a dentist or doctor's website should NOT be done in Flash. The reason for this is that some users don't have the Flash plugin installed, and there are some people who don't know how to install it if they need to. Thus, if you want to have an instructional demo of a procedure done with illustrations in Flash, I think that's a great use of the technology. But be very careful about using Flash for critical elements such as website navigation and contact information, because Blackberry and iPhone users will have a very hard time using your site because these devices can't "see" Flash.
Adobe has recently stated that they will no longer continue to produce Flash for mobile devices. This announcement does not by any stretch foretell the death of Flash on the desktop platform -- but it is a factor to consider. Since we are slowly moving to expand from the traditional "desktop" web to the "mobile" web on smartphones and other devices, it's not a stretch to think that at some point manufacturers and developers are not going to be as likely to work with a product that has no mobile future.
I always remind my clients that the iPad and the iPhone cannot view Flash content. What this means practically is that if there is something on your website that is only available in Flash then people using these devices will simply not be able to see your content. This caveat is ever more important now as new Mac computers are no longer going to be shipping with the Flash plugin installed. For most computer users this is not a tremendous hindrance - Flash is not that difficult to install. But now that Flash isn't going to be included by default on Mac's themselves, it's another reason to make sure that critical website content is available in alternative formats.
Flash is a ubiquitous plugin on the PC platform, and hence I don't predict the demise of Flash on the PC desktop/laptop anytime soon. Clearly I believe that your website needs to be device independent and you need to make sure that all users can view your important content (navigation, contact information). But with the end of Flash being included by default on Macs, it's ever more important that you make sure that your website is properly visible on this platform. I'm not recommending that practices with Flash navigation go out and redesign their sites. I would however, use this information as an "early warning" to take a quick look at your website on the iPhone, the iPad and on a Mac to make sure things look as you expect. The Mac still has a relatively small market share compared to PCs, but when it comes to iPhones and iPad, I believe that these devices will continue to grow in popularity. So while Flash isn't dead yet, I think the writing is on the wall and we all need to take notice.