Aside of the lacking availability of stable servers, another issue is that SPDY runs over SSL exclusively. That means that due to XP's lack of support of SNI, it's still not possible to do name-based virtual hosting.
Wasting an ip address for smaller sites is not always opportune or even possible, especially as we are running out of IP addresses.
Wasting an ip address for smaller sites is not always opportune or even possible, especially as we are running out of IP addresses.