For the past two years or so we have been testing out VDI in our residence hall student labs at UCSB which consist of about twenty or so thin clients split between two locations. Now what made all of this feasible was:
1) Advancements in remote display protocols
2) our ghetto-link-clones script (http://communities.vmware.com/docs/DOC-9020)
We picked HP's RGS as our remote display protocol because it was the only protocol we found at the time that ensured a "rich desktop user experience". I still prefer it today over the software implementation of PCoIP but that is a topic best left for another day.
Naturally, the only broker that pooled RGS-enabled machines at the time was HP's Session Allocation Manager (today Leostream and others can broker it). Despite bad experiences with some HP software in the past, SAM actually worked out very well for us, both on the server side as well as the client side. I still have yet to see a broker package that allows you to customize the client like HP SAM (this feature is definitely stamped as RAD in my book).
SAM was not perfect though and had the occasional hiccup (e.g. machines being listed as unavailable, annoying but only occurred once in a while and was remedied with a resync operation) until the day came: management decided to upgrade the domain from Win2k3R-something to Win2k8R2. SAM completely stopped working; it was an interesting situation to say the least.
After some testing (with profanity and throwing of objects included), we of course determined that the fault was in SAM (3.0, the latest release at the time in early January did not work). HP's response? No official timeframe to release a fix. This equated to a week of scrambling around looking for competing and "compatible" products (ala Leostream) which just ended up complicating things. The solution? An aggravating night biking back and fourth between the two labs switching the entire VDI environment over to View. Whatever it takes right?
So long story short, if you have an existing HP SAM installation that is running on a pre-Win2k8R2 domain, make sure you update to the latest revision of SAM (3.01) that was just released a couple weeks ago before migrating your domain to Win2k8R2.
For a short description of our VDI environment, please refer to: