Certain older Powermacs can be updated via a Sonnet card
to a G3 through these computers L2 cache slot. One such
Powermac model is the Powermac 6500. However, no linux
currently supports these L2 upgrades for these Macs, making
any GUI experience abysmal. Through an email
correspondence with Sonnet, it seems they may be willing to
release to source to an individual for the extension that
enables the G3 upgrade in Mac OS, in order for it to be
"ported" to linux, as long as Sonnet doesn't have to spend
their time and money to do so.