I got a Vodafone K3760 at some point in Debian/Lenny's lifetime, for use with a Lenovo S10e. I installed (from the Vodafone BetaVine site) usb-modeswitch 0.97 and vodafone-mobile-connect (VMC) 2.10.01-1 (or maybe it was actually vodafone-mobile-connect_svn20090615) and it all worked pretty well.
After the Debian/Squeeze update (2.6.32 kernel) I had some problems. Unlike Lenny, Squeeze includes usb_modeswitch 1.1.4-2, and I also grabbed vodafone-mobile-connect 2.25.01 (the latest version on Betavine targetting Debian-world distros). It does actually work... for a few minutes if you're lucky, before recurring kernel errors cause system lockup. However, with wired or wifi connectivity, the system works perfectly and is stable.
Enquiries in another forum led me to try the 2.6.37 kernel from Debian/Sid, and indeed VMC works perfectly with that.
This is a fine workround for now, but it'd be nicer to have a 100% Squeeze solution (I have little doubt that at some point over the lifetime of Squeeze, Wheezy/Sid will move on to the point that just saying "use the kernel from..." is no longer a viable solution). Is Debian/Squeeze's 2.6.32 kernel support for whatever VMC uses just plain broken ? Or is there something I can reconfigure in Squeeze/Squeeze's 2.6.32 kernel which might fix this up ? Is it my hardware (I'd be interested to hear if someone is using VMC with unmodified Squeeze anywhere).
Update 28/03/2011: Had a small hope that the 6.0.1 update to Squeeze (with minor a bump of the kernel from 2.6.32-30 to -31) might make things work better than the initial 6.0 release but no joy (any network traffic more substantial than ping quickly hangs system). So I tracked the sid kernel on up to 2.6.38-1-686 and VMC continues to work well with that.
Update 07/07/2012: I have another vanilla Debian/squeeze laptop I wanted to use the dongle with and thought I would try BCM on it instead of VCM this time (see one of the answers below). Made sure an older Python 2.5 was uninstalled and I just had Python 2.6 (saw a thread about this on the Forge site somwhere), then Installed the "beta 3" 2.99.12-1 deb with the accompanying python-messaging and wader-core (but not the modeswitch) and a few missing dependencies (e.g wmctrl and python-gudev) from squeeze... and it seems to be working very well. The most obvious oddity is that "Usage" always seems to log against the "3G" total even when connected by GPRS.