Since Cisco UCSs inception a few years back there have been many new features and even new products added to the library which all work really well with hypervisors. You might even say they were built to work with virtualization. As most folks are aware, there is the UCS B series which are blade servers that come in a 6U chassis. Small and large companies can use these, and although they can seem a bit pricey the total cost of ownership is really great given the savings on networking, licensing, administration, and management. However, if they still don't fit your wallet, you can also use the C series servers, which pack a ton of power and can still be managed centrally.
If you're an SMB or branch office you might look into UCS minis. These are a lot like blades, but take up a smaller footprint, have a great price point, but still pack most of the features of the B and C series. For larger companies, like hosted providers, check out the M series which is a modular solution and the C3160. The C3160 alone can hold up to 360TB of storage. Think about doing a distributed storage design with these. Imagine how many virtual desktops you can provision with this in your infrastructure!