While not yet there, they are getting better. This past week we added a third customer to Google Apps, converting their GroupWise 8 system and BES integration to Google Apps Premiere and BES. Ourselves. While we've done dozens of Google Apps Premiere migrations and turn ups for customers, the BES integration is new and only a few customers have it so far, as it has only been out for a month.
We found some issues and are working on resolving them with Google because the BES version is BPS (what we put a lot of smaller customers on, and it's not officially supported by Google yet). We needed to "live" in the same place as our customers. We gave up HTML rendering of email on the BB email client. Our simple workaround is, if we have an email we need rendering for, fire up the gmail client for the BB and look at it there, or get thee to a PC.
The only noticeable functionality lacking is the ability to put items on your BB calendar and have them also sync to the GAPPS calendar. Our workaround is to use the Google Mobile app, set the GAPPS DOMAIN in OPTIONS, and login to calendar (stays logged in). Then do a "quick add", and it will then post on your GAPPS calendar, which then syncs to the BB calendar. Google says to look for a fix in early 4th quarter.
It's worth a mention Google added pushmail to iPhone and Windows Mobile last week. "This BE HUGE". As long as Google Sync is enabled for the domain, you can sync a windows mobile platform by filling in the active sync fields. Sounds weird, but we suspect GOOGLE is looking at the User Agent data for the connection to their servers and translating as if it were Google Sync. So while the user is "using google sync" to do this, it is not installed on the Windows mobile phone itself.
On the iPhone, there is a Google Sync client to install, and it more or less handles contacts/calendar/email instead of using an IMAP connection for email only.
So with Google Apps now supporting pushmail for Blackberry, Windows and iPhone, all they have left to do is get tasks to work across all platforms (including Outlook) and two way calendar sync on the Blackberry done.
They are the only email vendor we are aware of that does push on the three major smartphone platforms. Of course Android is a smartphone platform, but it's already been completely Google-fied.