I use corporate Aventail VPN, with same "trouble".
All network traffic/control goes true several network Filter drivers, like in my case "Packet Scheduler Miniport", "Odyssey Network Agent Miniport", "McAfee NDIS Filter Miniport", etc. And to addition there is an "Aventail VPN Filter" driver under hidden devices in Non-Plug and Play drivers section, could be found in Device Manager.
Seems to me Aventail VPN Filter's aim is to sniff all network traffic and forward trough the VPN tunnel/connection/interface.
Just disable it, than you will get back the control on route table. At last you can add default gateway to your home network, and a persistant route to the corporate network.
Wikipedia about Filter Driver:
Filter drivers are optional drivers that add value to or modify the behavior of a device and may be non-device drivers. A filter driver can also service one or more devices. Upper level filter drivers sit above the primary driver for the device (the function driver), while lower level filter drivers sit below the function driver and above the bus driver.
2netstat -nr seems to work for OS X too. – Boy Baukema – 2011-10-10T18:54:41.803