I've been wanting to spin up an OpenBSD VPS for a while and finally got around to doing it yesterday.
Tried spinning up a 4.x last fall and there were some KVM issues. But 5.0 worked out of the box like a charm on a 128MB KVM from Hostigation.
The Realtek network interface is not supported under OpenBSD (you get constant "re0 watchdog timeout" errors), but the Intel PRO/1000 nic works just fine.
Next steps: - use config to lean/mean-icize the kernel to strip out unneeded drivers. On a bigger box I wouldn't bother but with only 128MB of memory, I'd like to squeeze out some megabytes. - pull out the pf manual to configure the firewall - modify /var/log partition to be append-only - I might play with immutable files once I get things setup the way I want. immutable files are a very nice *BSD feature - you set a kernel level so that the files cannot be changed without booting into the console. Typically used for core config files, firewall rules, etc. - play some more :-)
dmesg:
OpenBSD 5.0 (GENERIC) #43: Wed Aug 17 10:10:52 MDT 2011
deraadt@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC
cpu0: QEMU Virtual CPU version (cpu64-rhel6) ("GenuineIntel" 686-class) 3.40 GHz
cpu0: FPU,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,MTRR,PGE,MCA,CMOV,PSE36,CFLUSH,MMX,FXSR,SSE,SSE2,SSE3,CX16
real mem = 133742592 (127MB)
avail mem = 121569280 (115MB)