From the VT Tax website:

"The majority of states with sales tax and the businesses who sell into most of these states developed an agreement to simplify sales tax administration for states and to reduce the burden of tax compliance for businesses. The Agreement primarily focuses on businesses with limited or no connection that sell to the states’ citizens through mail order, catalogs and the Internet."

and...

Will canned software become taxable even when delivered electronically?
Yes, effective January 1, 2007 canned software delivered electronically is subject to the sales tax in the same
manner as software purchased in tangible form (CD-ROM, disk).