Since August, I've posted on and off about wm(4) not working correctly
on my T60.  I'm not the originator of PR 30078, but I had more or less
the same problem.  Now, autonegotiation works fine (to a linksys
EZXS88W 5-port 10/100 switch), and I get 96 Mb/s tcp throughput to a
modern box with on-board fxp0, and 68 Mb/s to a Thinkpad 600 with
Cardbus ex(4).  So I'm sure that all is well at least at 100baseTX
full-duplex.

Here's my dmesg:

wm0 at pci2 dev 0 function 0: Intel i82573L Gigabit Ethernet, rev. 0
wm0: interrupting at ioapic0 pin 16 (irq 11)
wm0: PCI-Express bus
wm0: 256 word (8 address bits) SPI EEPROM
wm0: Ethernet address [redacted]
makphy0 at wm0 phy 1: Marvell 88E1111 Gigabit PHY, rev. 2