It seems Google did an update to how it indexes Flash content yesterday. Some of you might have already heard about the headless Flash Player aka "Ichabod" that Google and Yahoo got from Adobe -- it seems it is now being put to better use. Google has been indexing Flash content for years, basically extracting any static text that might be embedded in there. If you do a search with the filetype:swf flag you'll see what that turns up.
Now with this new headless Flash Player, rather than trying to extract static data from the SWF file, it runs it over a command-line (non-visually) and gets back information about the contents of your Flash file, it will simulate button clicks etc. and capture the text results for indexing.
The important update now is that Google will also follow external resources, so for example XML files or other data that gets loaded in and not index it as a separate URL (as before) but in context to your Flash content. If you want to avoid your SWF files from getting crawled you can simply include them in a robots.txt directive like any other content.