I've used PocketMac Blackberry for quite a while, initially on a PPC machine and now on my MacBook. Version 4.0 does not work reliably; it hangs often especially when sync-ing my calendar file. Every once in a while I can get it to perform a full sync, but most of the time it doesn't. I wrote to the folks at PocketMac but they ducked the questions. To date, there's no sign that either they or RIM acknowledge that this product doesn't yet work well enough for business use.