You do have to hand it to Napster for getting a foothold and a first mover’s advantage in the UK. Of course, BuyMusic.com “scooped” iTMS for Windows, too… 
Of course, Napster’s a different case, being a credible if distant threat to iTMS in the U.S. As long as Apple doesn’t wait too long, I see some definite places where Apple can attack Napster in the UK *puts on armchair CEO hat*:
1) Apple could undercut Napster’s pricing. Not sure by how much, but surely folks in the UK know they’re effectively paying double (or more!) for the same music that people in the US are. After all, SuperDrive eMacs go for 699 pounds, not 999 (just checked ). If Apple can go 59 or 79 pence singles, and 5.99 or 7.99 pounds for most albums, it’ll bring in both the iTMS juggernaut and an ironic dash of price-undercutting WalMart to boot. You just know Napster wouldn’t like that. Even if it meant Apple would lose some money, it’d be a great loss leader, IMHO. I’m hoping iTMS would employ this kind of tactic…Roxio’s taking a necessary risk by making the first move, and given the disparity in each competitor’s resources, it’d be a great chance for Apple to keep the heat on by one-upping Napster.
2) Apple will blow away Napster’s selection. Apparently, Napster’s shown that UK music stores will be additive in nature, combining the US libraries with the UK ones. Napster might have 700,000 songs in 30 days, but iTMS could well launch with over a million…or at least 900,000 (existing catalog plus UK libraries). But wait…isn’t Napster’s true ala carte library less than the 500,000 songs it currently has? If you apply that logic to the 200,000 songs, that means significantly less than 700,000 songs for the non-subscription crowd.
By the way, doesn’t this mean that the iTMS US selection gets much bigger too?
3) Apple goes live in all of Europe within a couple of months. Bigger fuss, more deserved fuss, the Savior of the European music industry has arrived in full force. Oh, and I hear Napster’s available in the UK only too. And if the iPod mini launches worldwide at about the same time, even better.
Though Apple’s probably gonna lose some number of potential iTMS customers because of Napster’s outflanking, this is probably good news for Apple…a little competition can’t hurt to keep the market leader on its toes. With all eyes on iTMS US, I’m sure Apple will get a very welcome reception…and watch those song downloads skyrocket.