IBM’s definition of steal time is actually pretty good:

Steal time is the percentage of time a virtual CPU waits
for a real CPU while the hypervisor is servicing another virtual

So, relatively speaking, what does this mean?

A high steal percentage may mean that you may be outgrowing your
virtual machine with your hosting company. Other virtual machines may
have a larger slice of the CPU’s time and you may need to ask for an
upgrade in order to compete. Also, a high steal percentage may mean
that your hosting company is overselling virtual machines on your
particular server. If you upgrade your virtual machine and your steal
percentage doesn’t drop, you may want to seek another provider.

A low steal percentage can mean that your applications are working
well with your current virtual machine. Since your VM is not wrestling
with other VM’s constantly for CPU time, your VM will be more
responsive. This may also suggest that your hosting provider is
underselling their servers, which is definitely a good thing.

* I’ve been a customer of SliceHost for a while (prior to Rackspace’s acquisition),
and I recommend them to anyone who needs a solid VM solution. If you
want to help out with my hosting costs, you’re welcome to use my SliceHost referral link.