This thread is a bit old, so I'm not sure if I should even be resurrecting it, but nevertheless...
I have the same problem as well. I have a HTC, and on a previous version of Ubuntu (think I was using 9.04 or 9.10 the last time I connected my phone to my laptop) the phone recognised it was connected to a comp, and I was able to mount the phone as a removable drive.
Ignore what the version number says in the side, I'm actually on 11.04 (User CP won't let me update), and for some reason my phone doesn't even show the option to connect to PC. The computer recognises the phone though:
And in case you're wondering why it took so long for me to notice, I used to run Windows on my desktop, and the phone used to connect to that most of the time.
Bus 001 Device 022: ID 0bb4:0ff9 High Tech Computer Corp.
This is what dmesg shows when I connect my phone:
[70097.012091] usb 1-7: new high speed USB device using ehci_hcd and address 25
[70097.163603] scsi28 : usb-storage 1-7:1.0
[70098.168647] scsi 28:0:0:0: Direct-Access HTC Android Phone 0100 PQ: 0 ANSI: 2
[70098.170073] sd 28:0:0:0: Attached scsi generic sg2 type 0
[70098.202362] sd 28:0:0:0: [sdb] Attached SCSI removable disk