Do I Need to Upgrade to 3.1?
The short answer is, No. As the release announcement states, "please do not upgrade any of your production sites to the beta version as beta is ONLY intended for testing." If you do plan to test this version, make sure you are doing so on a development site.
By installing version 3.1 beta and taking it for a spin, you can also be an active participant in the Joomla development process. The main developers are always looking for more people to find bugs and issues to report back so they can be fixed. Helping in this way can create a great sense of community for you and can also make Joomla an even better product.
What's This About Tags?
The feature that most end users will find most interesting is Tags, and no it doesn't have anything to do with shopping...unless you're running an online store perhaps. This is something the Joomla community has been waiting to have in the core of the CMS for a while. Nick Savov describes the new feature in a blog post on The Joomla Community Portal this way, "Tags are a kind of meta-data that allow you to assign a keyword or keywords to a particular item."
So, what is this meta-data stuff? The easiest way to describe it is to say that it's data about data. It is used to describe something like an Article or other content in your Joomla website. The great thing is that it can also be used by other extensions to do some nice things like filter information and show related items very easily. Now that it will be in the core of Joomla, we won't have to install other extensions to do this.
For instance, if you have a website about coffee, you can tag certain Articles with information like "free-trade," "dark roast" or "espresso." You can then use that information throughout your website in some very meaningful ways.
What Else is New?
While Tags are definitely the new shiny toy for this release, there are also a couple of other items that some users, especially developers, might find useful. You will now be able to show logs in the debug console, add pagination in the COM_SEARCH component, among other additions.
The code base should also be somewhat leaner now that the GeSHi plug-in is being removed. This was a plug-in that allowed the presentation of highlighted code based on specific languages, such as PHP, CSS and HTML.
If you do choose to install these beta versions, consider becoming a part of the Joomla! Bug Squad. They are always in need of help, and your participation will again help to improve Joomla in a big way.
You can also read the entire 3.1 beta announcement on Joomla.org