Here's something interesting.

So, you've already seen the BattleTag™ announcement. And you'll notice the TM symbol attached to every little instance of BattleTag™.. so it's a trademark owned by Blizzard right?

Apparently not. UBISOFT ENTERTAINMENT owns that trademark. :)

It's an old filing (2010-06-09), and there hasn't been much activity until just this week. Oddly coincidental.

They filed an "Intent-to-Use" report with the US Patent and Trademark Office, which was just received 2 days ago. So, UBISOFT wants to start using their "BattleTag"/"Battle Tag" trademark too.

There's also another older trademark for BattleTag by another business, but it's just for wireless devices. The UBISOFT one is for entertainment services, computer games, LAN services, etc.. so it matches with what Blizzard wants to use their Trademark for. And, UBISOFT owns the TM in Europe too.

I guess this leaves a few possibilities:

1. UBISOFT is a typo in TM database. (Very very doubtful.)
2. Blizzard bought the TM from Ubisoft, and the changes aren't visible in the TM DB yet.
3. Blizzard is getting a "BattleTag" trademark instead of "Battle Tag". Still, a punch in the face to Ubisoft since they intend on using it too.
3. Ubisoft is going to make a stink about the trademark (TM infringement). It's too similar: "Battle Tag" vs "BattleTag". And, it would be funny if they use it themselves in the same way Blizzard intended.
4. Blizzard might change the Battle Tag name to something else.

Blizzard would have known all about the Ubisoft TM well in advance, though, before using the name.. so I wonder what's going on?

Blizzard is also using both wordings "BattleTag" and "Battle Tag" in their posts (Ex 1 & Ex 2) about the service. And, Blizzard users aren't making the distinction either (so this "confusion" could actually help Ubisoft if there was a legal case.)

Seems awfully coincidental too that Ubisoft wants to suddenly start using the trademark.

There's also a 5th possibility.. but I don't even want to consider it. It's too scary.