The first question that pops into the mind of people is "if you already have a connected laptop, why do you also need to use a PDA to connect to the net"? Well, there are lots of reasons why this can happen:
1. Your partner needs to do some work via it, while you are browsing osnews vigorously. ;-)
2. If you are a web developer, test your web site with its mobile browser(s), and we are not talking just AvantGo here which happens to work as both offline and online browser.
3. Allow the person with the PDA/Phone to check his personal pop3 email without having to setup a user account on your Mac.
4. Stream Bluetooth LAN access up to 7 people (e.g. in case all your friends have BT PDAs).
5. Stream music via iTunes to your mp3-enabled PDA for up to 7 BT clients, all at once! Think: washing plates in your kitchen and you want to listen to some music off your desktop, something that your 128 MB mp3 player doesn't handle.
6. Allow PDAs and phones access your network.
7. Your partner might have a laptop without wireless (e.g. PC laptops or older iBooks), but it's easy and cheap to get a $20 USB BT dongle. Your Mac could share its connection to your partner's laptop when on vacations.
8. If your Mac Access Point is a desktop Mac (and hence you can't move it around) and you want to use your PDA or old iBook or other laptop (that has no Wifi, but just a BT dongle) outside in your veranda while you are drinking that refreshing smoothie, that would be the way to do it.
9. Because it's cool to know that your computer is able to do this.
The second question that might pop to your mind is: "why don't you buy a Bluetooth LAN Access Point?". Unfortunately, that's not a great advice, because if you are away from the office/home, you don't want to carry it with you, plus the cheapest one costs about 70 bucks, which is far more expensive than the $25 WiFi routers available today.
The third questions you have is "why don't you use a BT phone to connect your PDA on the net"? The answer is three fold:
a. I don't want to pay for phone calls for slow internet access via dial-up
b. I don't have a Bluetooth phone
c. I don't have a mobile phone or a BT modem ($80) in general.
For the last month I scoured the net to find ways to route net access to a BT device via a Mac. Apparently a lot of people are asking for that feature, and while it IS possible via some command line magic, it's an extremely delicate procedure and it seems to break (or commands need to be modified) from OSX version to OSX version (even minor versions).
For example, there are FOUR third party ways to do the job, one via IPShareNetX which does not work anymore (in fact, it doesn't even autodetect my Mac's integrated BT anymore), the Share2Blue2th Applescripts that also don't work anymore (plus it's point to point and it doesn't do routing for up to 7 clients), the P800 hack that also doesn't work properly anymore (at least not with non-P800 phone devices), and finally the Bluetooth2Internet utitlity ALSO does not work anymore (the v3.0 is expected to be released since forever).
Then, there is the manual way that somehow don't work for everyone and it requires lots of extra tinkering even after you followed the instructions here or here or here or here. Also, some of the stuff suggested there are outdated. Addtionally, this is just not the Mac way and I refuse on principle to spend hours just to get something like that working. I'm not interesed in doing this as an exercise in hacking, but rather out of a true desire to enjoy this functionality.
Now, on the other side, there is the Windows and Linux way, where it IS possible to route over BT, and it's even easier to setup than on the Mac (even Linux does it easier it seems). Thing is, I prefer to take with me the 12" 4.6lbs Powerbook when away, rather than the 7 lbs 15.2" LinuxCertified laptop (which doesn't have built-in BT anyway, though my brother bought me an external USB BT dongle, for my name day :).
The other kicker is that Apple has put some substantial work on making Internet Sharing work over Ethernet, WiFi, modem and even over a Firewire cable. But there is no support for Bluetooth sharing. The pref panel allows you to share a Bluetooth connection, but only to computers using WiFi or Ethernet. What I need is the ability to share a modem/WiFi/ethernet connection TO computers that use Bluetooth. This option is not available and that's why all the fuss is happening.
I don't know if Tiger will support this functionality (crossing fingers), but somehow I doubt it will (in fact, my sources say that the feature is still not there). Hopefully, a dedicated third party software maker will build such a utility, which should not be hard to write (it's been done before), it's just that it would need constant updating & testing when new versions of OSX are released every 2 months. That's the commitment users would need from such a software utility.