Currently, when I enter a search term it does not appear to search tags that have been applied to features. I'd like to be able to see a list of all features that have the tag I'm searching for. Ideally I'd be able to search at any product level as well; it wouldn't be limited to the parent product line.
From the Feature list (or Report List page), you can create a table with this exact functionality. You can create a Features table which includes the Feature name, tags and other critiera. You can also filter on specific Tags to see exactly which features have the tag that you are interested in. This can also be filtered by product (and many other data points)