We too have been going this route - I caution you against Polycom right now as they are currently not friendly to OCS end-users...for instance, you need to be a reseller to get current phone ROMs and other software.
Microsoft will be coming out with actual hardware devices to support the OCS roll-out - suggest you expend you energy on getting ahold of one of those (and if you can I'll buy one from you!). In working with MS for over a year on this I was not able to achieve that and as such am being force to evaluate non MS solutions. A quick search on "Microsoft Roundtable" will yield a start.