I attended the Zimbra Mobile webinar last week. Although the ActiveSync works fine, and I'm sure a lot of people, myself included, will be very keen on using the upcoming iPhone 2.0 with ActiveSync support built-in, a lot of my current and potential customer have BlackBerries and are likely to stick to them. I've successfully implemented BlackBerry Professional Software (BPS) on a limited basis through ZCB Beta. Generally it works fine, but I have had some issues similar to what many others here on the forum are describing.
A native BES/BPS would be great. Perhaps Yahoo!/Zimbra can create some kind of online "petition" to show RIM that the Zimbra community really wants a native BlackBerry solution for Zimbra on Linux?