I'm running Ubuntu 11.10, FF 11, ATI Catalyst v12.2, Driver Package version 8.95, WebGL doesn't work.
This is a pretty capable setup and definetly did have FF work previously, Note: I've downloaded and installed the ATI drivers from AMD. Not sure how to get WebGL working.
My video card info:
01:00.0 VGA compatible controller: ATI Technologies Inc Cypress [Radeon HD 5800 Series] (prog-if 00 [VGA controller]) Subsystem: ATI Technologies Inc Device 0b00 Flags: bus master, fast devsel, latency 0, IRQ 44 Memory at d0000000 (64-bit, prefetchable) [size=256M] Memory at fbee0000 (64-bit, non-prefetchable) [size=128K] I/O ports at d000 [size=256] Expansion ROM at fbec0000 [disabled] [size=128K] Capabilities:  Power Management version 3 Capabilities:  Express Legacy Endpoint, MSI 00 Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities:  Vendor Specific Information: ID=0001 Rev=1 Len=010 <?> Capabilities:  Advanced Error Reporting Kernel driver in use: fglrx_pci Kernel modules: fglrx, radeon