Hi
No, I think the situation is still the same. This Intel RAID is really co-operation between the motherboard and the OS to provide RAID (unlike a RAID controller where the OS doesn't know there's RAID underneath) so the OS needs to support it. In the case of ESXi 5 it didn't and I'd be surprised if 5.1 was any different but would be happy to be corrected 
I think your options are:
- to do software RAID within the guests,
- use some sort of virtual appliance like NexentaStor to present iSCSI or NFS shares which it RAID protects - though you still need something to protect the VMFS running the appliance,
- buy a RAID card and plug your disks into that. (I know it seems a shame given the supposed motherboard RAID support!)
Actually the last of those might be easiest approach and not that expensive (50-100 EUR?) - the main thing to do would be to search for people using your make/model of RAID card with ESXi before you buy it (ESXi probably won't have the drivers for the very cheap ones).
Good luck!
Simon