Thanks, I'll try to dissect that python script and try to reproduce results via some shell one, when I got time. As for your question, I'm using Viqsi's method (with your fixes, as I belive, already incorporated into original post) + corrected /usr/bin into /usr/sbin.

The result is, that it *doesn't* automatically connect GPRS for me during PAN initiation (maybe something about not having GPRS set to auto-connect when internet is demanded from programs, in Maemo?), but if I connect/disconnect GPRS manually while PAN is active (and clients are "leeching" net access), changes are propagated seamlessly. No need to reconnect anything bluetooth related, tethering clients reach internet as soon as host ("main" N900) can reach it.

/Estel

// Edit

I just re-read your post, and obviously, I missed the "without touching N900" part, so I think that you're also *not* having problems with auto-propagation of network access change, and you're thinking *only* about more robust way to keep GPRS alive during PAN usage, even after disconnects.

What about something like:
...which would be called only when PAN network is "alive"? It should result in "watchman" script sleeping in background, getting alive only if GPRS disconnects, trying to reconnect it after 5 seconds, then.

/Estel