I've tried resets, reboots, turning Match off and back on, deauthorizing and reauthorizing my computer - just can't process any new songs. It sticks at "0 of X songs checked" and doesn't go anywhere. No songs with Error status, new additions are just 'Waiting' forever.
Server problems in light of all the new countries added - could be. I emailed Apple, they're suggesting it's a known issue, and to clear any songs with an Error status. I have none.
As a 'control' I tried deleting a previously successfully matched file from my computer and from the cloud, and re-importing it. Same thing - it won't match or reject the file, it just sits at the beginning of step 2 forever. If a file that imported/matched fine last week isn't working now, it's unlikely this has anything to do with the files themselves.
I'm not exactly hooped, I've got about 3000 songs in my cloud (everything worked fine until yesterday) but not being able to import anything new is a drag - I still have a couple hundred CDs and gigs of old MP3s I'd like to import.... hmmmmm...