I've recently noticed that it is becoming more and more common to see 'weird' MAC addresses, i.e. MAC addresses which do not start with numbers 00. Previously it was very easy to spot automatically mentally software defects which would cause strange MAC addresses to appear, it has helped me to diagnose several issues in the past. We've now beginning to lose that advantage, as IEEE has started to allocate MAC addresses quite randomly across the address space.
I emailed to IEEE and asked what was the motivation and perceived advantage in doing this change and reply was quite simply 'We changed our allocation methods to prevent vendors using unregistered mac addresses.'. OUI costs 1650USD one time fee, but IEEE appears to be concerned that some vendors choose not to pay it, instead allocate themselves OUI somewhere far in the address space, effectively thinking they are getting free OUI with little to no possibility of overlap. It would be curious to know if this instance who wants to save 1650USD would care about this slightly changed climate, I personally doubt the change while good-willed is completely ineffective and the slight operational benefit serial assignment had is lost. (/me starts crying over spilled milk).
In slightly related note regional IXP here is using static manually assigned MAC addresses from 4000.0X, where X is the number of the IXP site which is then followed by base10 of ASN and then free 4bits for user. So in site 1 for AS4242 would be 4000.0104.2420. Unfortunately when these were assigned someone mad mistake with bit significancy order and this MAC address is not locally assigned as was intended but normal public MAC address. I'm recommending new scheme of xEzz.yyyy.yyyy. Where 'y' is the ASN in hex (supporting 4byte ASN), 'z' is customer assigned, 'E' is static and 'x' is IXP site number. E could be also 2, 6 or a, but 'E' for exchange is kind cute.