Somedays ago i update OpenBSD 4.0-beta on my laptop to -current and enable ACPI support in kernel config. Now i have one sensor. ;)

saturn:~% sysctl hw.sensors
hw.sensors.0=acpitz0, zone temperature, 52.05 degC

Here is diff against 4.0-beta and -current with enabled ACPI `dmesg':

-OpenBSD 4.0-beta (GENERIC) #1055: Thu Aug  3 11:39:24 MDT 2006
-    deraadt@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC
+OpenBSD 4.0-beta (GENERIC) #5: Thu Aug 24 22:02:02 MSD 2006
+    dmitri@saturn.openbsd.pp.ru:/usr/src/sys/arch/i386/compile/GENERIC
-avail mem = 228171776 (222824K)
+avail mem = 227909632 (222568K)
+acpi0 at mainbus0: rev 0
+acpi0: tables DSDT FACP HPET BOOT
+acpitimer0 at acpi0: 3579545 Hz, 24 bits
+acpihpet0 at acpi0: 248348 Hz
+acpiec0 at acpi0: EC0_
+acpibtn0 at acpi0: LID_
+acpibtn1 at acpi0: SLPB
+acpicpu0 at acpi0: CPU0: 1500, 600, 0, 0, 0 MHz
+acpitz0 at acpi0, critical temperature: 100 degC
-cbb0 at pci1 dev 6 function 0 "Texas Instruments PCI7XX1 CardBus" rev 0x00: irq 10
+cbb0 at pci1 dev 6 function 0 "TI PCI7XX1 CardBus" rev 0x00: irq 10
-ichpcib0 at pci0 dev 31 function 0 "Intel 82801DBM LPC" rev 0x03: SpeedStep
+ichpcib0 at pci0 dev 31 function 0 "Intel 82801DBM LPC" rev 0x03: failed to map I/O space
-biomask effd netmask effd ttymask ffff
+biomask edfd netmask edfd ttymask ffff
-auich0: measured ac97 link rate at 47998 Hz, will use 48000 Hz
+auich0: measured ac97 link rate at 48001 Hz, will use 48000 Hz

And here is link to short note about trunk(4) interface in OpenBSD 3.9: Using trunk(4) interface in OpenBSD