Just saw this over at hackaday and thought I'd share. Haven't tried it out yet so I can't tell you if it works, did a quick search of the forums and didn't see anything...
Blackberry download limit remover - Hack a Day
hxxp://hackaday.com/2009/09/01/blackberry-download-limit-remover
Can't post links yet...
Cheers
[ update ]
Was just looking at this and it looks like if you do it you'll need to re-send your service books as this overwrites them. Seems to work but try at your own risk I guess.
Dangerous, it exposes all your traffic through a Chinese network. Does anyone else see this as a security risk?
There is also the possibility it will bring a very nasty surprise with billing for out of bundle data usage. Individual service provider policies may vary on this but I would expect excessive cellular traffic to be noticed and investigated.