Like the presidential seal that vanished without comment from a politician's press podium, the competitive marketing brickbat that Apple flung at BlackBerry -- that BlackBerry's push e-mail works only with Microsoft Exchange, as if Exchange were an onerous burden -- quietly vanished from Apple's campaign.

Exchange Server turns out to be the only customer-hosted messaging back end supported by iPhone 3G and first-gen iPhones running 2.0 software. It's true that BlackBerry requires BlackBerry Enterprise Server (BES), but BES integrates with Domino and Groupwise as well as Exchange, and BES works transparently with non-BlackBerry devices through BlackBerry Connect. I'll always be here to set the record straight.

If you balk at the extra $3,000 to $10,000 it takes to strap BES onto Exchange, then your needs are more basic. You may be best served by a third-party hosting provider, but even that can be overkill for individual professionals and small businesses. RIM's solution for individuals is BlackBerry Internet Services (BIS), its own hosted push messaging. BIS is bundled free with T-Mobile's BlackBerry coverage plans (I can't speak for other carriers), and it replaces an earlier consumer-targeted service that included a Web-based mail reader and server-side message filters.

I liked that service, but it carried a stringent limit on mailbox size, which BIS does away with, in addition to the Web interface. On T-Mobile's network, messages aren't stored where you can get at them using anything but your BlackBerry, but BIS can keep an unlimited number of messages in flight until they're either fully delivered or they bounce to the sender after several days of failed delivery. BIS can maintain multiple mailboxes for each subscriber, with separate folders on the device's home menu and dedicated client-side filters (for example, vibrate for VIP messages even when the phone is in quiet mode). You can gateway POP3 mail through BIS, and although POP isn't inherently push-capable, once BIS picks up a message, it follows the same assured delivery path as any other BlackBerry missive.

Anything that's free comes with a catch, and in the case of BIS, it only handles e-mail. You can send and receive appointments and individual contacts packaged as standard e-mail attachments, but they don't hit your calendar or address book until you open the attachment. Also, unless you're running BES, your calendar and address book live only on your device until you manually back them up on your desktop. BIS affords users no gateway to the sort of live collaboration, shared folders, and instant messaging offered by Exchange and BES. That's why "enterprise" is BES's middle name.

Apple didn't frame .Mac, its subscription-based online service for Mac clients, as a solution for professionals. However, Steve Jobs touts .Mac's evolved form, MobileMe, as "Exchange for the rest of us" -- quite a boast indeed. MobileMe, which costs US$99 per year or $149 for a five-user pack, is the only way non-Exchange users can get push e-mail to their iPhones. MobileMe has that in common with BIS, but the similarities end there.

I am a longtime .Mac subscriber, so I'm familiar with MobileMe's features: 10GB of sharable online storage, slick AJAX mail, address book and calendar clients with sweet touches like recipient completion, the requisite personal Web site/blog, and photo gallery.

Fairly recently, .Mac took on a couple of new roles custom tailored for professional users. It provides manual or scheduled synchronization of contacts, bookmarks, appointments, mail rules, and mailboxes (not messages) across multiple Mac clients. Everything synced with your Mac is reflected immediately in MobileMe's Web interface. Back to My Mac, also relatively new, is a secure screen-sharing gateway that burrows through residential Internet providers' NAT and router firewalls. For those of us who have more than one Mac, .Mac is our sanity's savior. MobileMe is at least that.