Fellow Sun Intern Victor Castillo sent out this fantastic summary of the capabilities and features OpenSolaris offers for physical and virtual networking. I am republishing it in its entirety here, because I think it is a great summary and could help a lot of students looking to give it a try!
"I'll start with Crossbow (http://hub.opensolaris.org/bin/view/Project+crossbow/WebHome): Crossbow is the basis for network virtualization and resource control in OpenSolaris. It allows you to create virtual NICs to be used either by a networking service (HTTP, FTP, and others) or by virtual machines (Zones, VirtualBox...). Each of those vNICs has it's own priority and assigned bandwidth in order to guarantee QoS (via Flows) and prevent DoS by isolating the effect of any attack to just one vNIC and not the physical device. Crossbow also allows you to create a virtual switch connecting the vNICs, so you could create a complete virtual network inside OpenSolaris (called vWire). A GUI to build and test the network-in-a-box has been released and while it is at alpha quality at the time, it works nicely for demoing and testing: http://blogs.sun.com/observatory/entry/crossbow_virtual_wire_demo_tool . Also of interest, after the inclusion of Crossbow in OSol, similar solutions have been announced for inclusion in FreeBSD (http://itmanagement.earthweb.com/osrc/article.php/3835846/FreeBSD-to-Upgrade-Routing-Architecture.htm) by Blue Coat and in Linux (http://openvswitch.org/) by Citrix, proving how OpenSolaris is once again ahead of the competition.
Recently, the Integrated Load Balancer (ILB: http://wikis.sun.com/display/OpenSolarisInfo/Integrated+Load+Balancer) has also been added to OSol (http://www.c0t0d0s0.org/archives/6072-Loadbalancing-with-Opensolaris-or-PSARC-2008575.html), adding L3/L4 (transport and network layers) load balancing to the OS by default.
Project Clearview (http://hub.opensolaris.org/bin/view/Project+clearview/WebHome) includes components such as re-designed IP tunneling and IP Multipathing (IPMP) for better behavior and observability of the networking devices. The final component of Clearview (IP Tunneling DD) were integrated in Nevada build 125 (http://blogs.sun.com/seb/entry/clearview_ip_tunneling_in_opensolaris).
Integrated Quagga (http://www.quagga.net/), IP Filter (http://coombs.anu.edu.au/~avalon/ip-filter.html, http://blogs.sun.com/tonyn/entry/firewall_configuration_in_opensolaris_2009) and IPSec (for network routing, firewall and packet authentication and encryption (including VPN tunneling). (http://docs.sun.com/app/docs/doc/819-3000/ipsectm-1?l=en&q=mobile+ip&a=view)
And of course, DTrace can be used to debug networking problems (http://hub.opensolaris.org/bin/view/Community+Group+networking/dtrace_networking_cookbook)
It's important to remember that all of these capabilities can be used simultaneously, according to our needs. One example of this is the Virtual Network Router appliance project ( http://hub.opensolaris.org/bin/view/Project+vnm/VNRP) that combines Crossbow, Quagga and Zones (and all managed trough Webmin: http://www.webmin.com/) to create an integrated edge-router, to separate intranet traffic from internet traffic.
For further reading, you can visit these links:
http://hub.opensolaris.org/bin/view/Community+Group+networking/WebHome
http://www.opensolaris.com/learn/features/networking/networkall/
check the attached presentation, and also, check the Storage Projects for information on different connectivity options that OSol offers (pNFS, NFS, FC, IB, iSCSI among others): http://hub.opensolaris.org/bin/view/Community+Group+storage/WebHome."

