Though I may not know how the assessment is been done but the application did list down a few things which will be used as a consideration.
I read up the vExpert 2012 application here. I will also list down what allows you to be consider a vExpert in order to apply before the page get removed since results of vExpert 2012 has already been released. The shorter criteria description can be found here.
Below are the three ways you can be assessed and the benefits of been designated:
The Evangelist Path includes book authors, bloggers, tool builders, public speakers, and other IT professionals who share their knowledge and passion with others with the leverage of a personal public platform to reach many people. Employees of VMware can now also apply via the Evangelist path.
The Customer Path is for internal evangelists and community leaders from VMware customer organizations. They have contributed to success stories, customer references, or public interviews and talks, or were active community contributors, such as VMUG leaders.
VPN (VMware Partner Network) Path
The VPN Path is for employees of our partner companies who lead with passion and by example, who are committed to continuous learning and to making their technical knowledge and expertise available to many. This can take shape of event participation, video, IP generation, as well as public speaking engagements.
Public recognition of the vExpert award with a certificate, gift, permission to display a logo, and inclusion in any public vExpert listing
Access to a private vExpert community of your peers
Free subscription to conference session materials on VMworld.com
Access to exclusive events, beta programs, software licenses, and other exclusive opportunities to participate in activities with VMware. vExperts do not represent VMware and are not required to participate in any activities
Now to my experience. I started doing professional services back in my IBM days. Been VMware my forte I was given many opportunities to implement and support many of my customers. However I do not do this alone. I was enabled by the help of the community and people in the field who are willing to share.
What makes me want to return back to the community after gaining so much you might ask? Since I gain from it it is only fair I return this as well to benefit the others. One person who got me to doing this is one unknown guy I know from VCP Discussion group in LinkedIn,