As new player in virtualization field VirtualBox already reach version 1.5.2 .
What VirtualBox have done so far?
Is it good as vmware or Virtual PC?
Dunno, by seeing its implementation You can judge
Googling and forum searching, I found :

Create and Manage Virtual Machines Using VirtualBox, VirtualBox is a general-purpose full virtualizer for x86 hardware. Targeted [...]

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We are proud to announce the version 0.3 of GNS3, this version is considered as a beta.
A lot of new features and bug-fixes are available, the most important are:
- Support of Ethernet, ATM and Frame-Relay switches
- Included hub (Bridge of Dynamips) and cloud (external connections) devices
- Added the Dynagen console (nearly [...]

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From Greg blog :
Continuing my quest to avoid a 1.0 release at all costs, here is version 0.10.0. The most important things in this release are support for 1700 platform [...]

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From Cris blog :
Hello all,
The 0.2.8-RC1 release is available. It requires a Dynagen upgrade since the hypervisor control protocol has been modified. The new Dynagen release will be published by Greg soon.
New features:

Support of the Cisco 1700 platforms, with WIC-1T, WIC-2T and WIC-1ENET cards (as for the 2600, the images need to be uncompressed before [...]

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