It's just a starter card. Depending on the size and compression you choose for your images it'll hold anywhere from 9 high quality to 137 tiny ones. It's all included on the camera review on this very site.
You'll want to get a larger card ASAP, something 256M or higher.
People very often complain of the small memory cards included. (including most reviews here) I really don't believe that's a fair complaint though. Just as with film cameras (remember them?) You probably weren't supplied with film unless you were buying a disposable or an entry level camera "kit".
A 16MB card is there only for the "instant gratification" to see that your new camera works/how well it performs if you haven't already purchased memory cards for its use. Also, they'll work great for in-store demos. That's it.
Now consider that you can find 256MB and 512MB cards very inexpensively after rebate, and for under $30 you should be able to take 100-200 or so pics at 5MP. Were similar cards bundled with a camera, expect the full retail cost (~$35-75) would be tacked on to the camera's price. This would be somewhat irksome if you already had a few large compatible cards on hand from a previous camera.
Someone who uses their camera for special events/around the house probably only needs a 256MB card. On an extended vacation, you'd probably want at least 512MB. A professional sports photographer may need several high speed 1GB or larger cards. It just makes more sense to make memory cards a separate purchase.
A lot of camera retailers offer a variety of starter packages that include the camera along with memory/case/tripod/batteries/lenses/etc. they might be a worthwhile value if you need everything that's offered and you like the particular specs provided. For a camera manufacturer to seal a one size fits all package into a "prosumer" package would probably generate many more complaints than the puny memory cards currently receive. It's true that you can't please everyone, but by providing a "sample" card that will take 3-7 pics, they should be able to please most people. </soapbox>
I wasn't complaining about the practice of including a small starter memory card in the box, just saying that it's not really worth worrying about how many images it holds since you need to buy a larger one.