Apple’s Developer Center is now allowing certain developers to add up to 200 iOS devices to their account, double the previous amount allowed. Devices registered in this list can beta test a developer’s applications as well as the unreleased versions of iOS (and related software like iTunes).

Developers have been wanting the limit to increase for quite some time, since removing a device does not increase the count again until membership is renewed:

As seen above, Apple’s documentation still reflects the 100 device limit and there has not been a new post in the developer center news, so the new limit may be a fluke or something that is rolling out to specific developers only.

How many iOS devices can I register for testing and Ad Hoc distribution?

You are allowed to register up to 100 iOS devices for testing and Ad Hoc distribution per membership year.Please Note: Although you may remove a device from your account, it will continue to count against your 100 device limit.

(Thanks, Mr. Cool Guy!)