I've seen numerous discussions about the new Google Apps for Blackberry as well as enhanced Gmail, and just want to throw out my 2-cents.
As a small-business owner (and what might be considered an OCD blackberry user), I've tried pretty much every alternative to using an Exchange/BES setup to get my email delivered with the speed I require for my business.
A number of years ago, I decided to stop hosting my own BES b/c the upgrade costs and hardware demands to make it stable (servers don't like lightning) were a huge PITA, so I started looking for outsourced hosting. I ended up going with themessagecenter.com and have been with them ever since.
I'm not going to be paid for mentioning them, have no financial interest in them, and am mentioning them strictly because I've never before seen technical support folks that are as responsive, friendly, and effective as these people.
If you're a small-business owner that doesn't want to deal w. hosting an exchange server (or paying for the software upgrades) but needs a very robust email platform, I'd suggest you check out TheMessageCenter (themessagecenter.com).
You can sync your blackberry using a google setup via the BIS and get close to Exchange functionality (assuming your domain host can use one of Gmails ports), but if you're looking to exactly replicate Exchange without paying the fees required to host your own Exchange/BES setup, I'd check out TMC. Extremely cost effective (I'm a one-man show and do everything I can to minimize costs). Extremely high-quality tech support (I'm talking real people...not script-readers). And extremely reliable.
Now I'll get off my pulpit. One more time for the record though, I'm not a "paid promoter", I just recently had a tech support issue that TMC was so helpful with, I felt it was about time that I mention them as a really good alternative to those contemplating switching from an in-house Exchange/BES setup to a google-apps alternative to save money.