It's been a big week for the smartphone. First, Palm

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[PALM  Loading...      ()   ] rolls out its latest model, the Pre. Then, Apple

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[AAPL  Loading...      ()   ] comes out with a $99 version of the iPhone.

And, as if that isn't enough, The New York Times ran a feature on smartphones that found them to be one of the few items that are still selling in the recession—despite the cost of the units and the monthly charges.

Summing up the benefits of the all-singing, all-dancing devices, one source cited in the Times piece described how he purchased his iPhone to help with a job search after recently being made redundant. Now, he says, "It allows me to be on top of things, and always connected, no matter where I am."

Clearly we're looking at a growing trend: the Times piece reports that the number of BlackBerry users has almost doubled in the last year alone, to 25 million, while Apple reached 17 million iPhone sales in March, and is probably already past the 20 million figure.

• Read more: CNBC's Tech Check with Jim Goldman

Providing constant access to email and information, they’re the perfect tool for businesspeople on the go, with even the President coming over all Charlton Heston-like at the thought of losing his when took office.

Wherever there are new technologies, however, problems and questions of etiquette will surely follow—and that goes double when the technologies in question further erode the boundary between work and private lives.

For that reason, I've taken the time to compile a list of things to bear in mind when using a smartphone in a business setting.

1) Don't use them in meetings

Sure, it's tempting. An email comes in and just begs to be dealt with—and the more habitual the user, the harder it is to ignore the siren call. Before giving in, consider how the other people in the room are likely to react to having less than your full attention. Think that's petty? NY Senate Majority Leader Malcolm Smith probably did too, but he's likely regretting it today.

2) Make sure it's secure

If a device can operate as a mini-computer on the go, it stands to reason that you should protect it just as well as you would a computer. Secure passwords and encryption are a good start, as is never letting the thing out of your sight. Just consider how big a problem it would be if your personal or corporate information fell into the wrong hands. Cleaning out the cache memory from time to time won't hurt either, and is an important step to take to avoid other people being able to visit sites you've accessed from the phone and glean potentially sensitive information.

3) Remember who owns it

If your phone came with your job, bear in mind that you're probably going to have to hand it over when you leave—and likely with very little notice, if you're being laid off. For that reason, backing up personal data saved on the phone, including contacts, is every bit as essential as doing the same thing with files stored on work computers.

4) Know your limits

Just because you can send an email to an employee at two in the morning on a Saturday doesn’t mean you should expect a reply by 2:15. Especially if said employee isn't a smartphone user. Likewise, having round-the-clock access to incoming email shouldn't mean that you're expected to answer it round the clock. Here's a big tip: locate and learn to love the off button.

5) Separate work and personal life

Most people know the difference between internet applications they use for work, and those that fit in the realms of their personal life. Most companies know the difference too, with the tactic of restricting access to certain websites long since established at certain firms. That's another barrier being toppled by the smartphone, with people now gaining the capability to access their favorite sites even from a cubicle where the desktop computer can't. Again, though, just because you can doesn't mean you should—you wouldn't be the first person to get canned for checking Facebook from your iPhone.

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