Relocated to US from canada on a L1 work visa. I paid 1/2 of the cost of the visa, as well as the application fee at border immigration. I will be filing US taxes. Are the above work visa cost deductible in my tax return?

No visa cost and application fee are not deductible. But if you plan to stay in the job for minimum 39 week in the year after relocation, then you can deduct Moving Expenses.
Read: Your U.S. Tax Return: Moving Expenses (http://taxipay.blogspot.com/2008/02/moving-expenses.html)