Wow BIS is finally getting a significant feature bump with v4.1. The team at N4BB managed to score slides detailing all of the features coming in BIS 4.1 along with rollout dates. Some of the features are also BlackBerry OS 7.0 specific which should be launching around the same time. According to their sources BIS 4.1 will be rolling out to Asia Pacific on Sept 10th, Europe on Sept 23rd, and North America on October 8th.
I am really excited about the new features including my favorite which is email inbox priming. That is a feature that has been available on BES servers for awhile giving you access to your last chunk of emails. With BIS 4.1 it will preload the most recent 20 emails so you will have conversations on your device preloaded. There are loads of other goodies including better account management and message improvements for OS 7.0 so check them out in the slides!