I can think of a lot of companies that would be better shorts than JNPR. But you have hit their real weakness -- weak market segment.
Juniper hires the best people in the business, they have the best products in class, they are expanding their product lines, best software, etc... However, there is a definate lack of customers to purchase their products. Their markets will recover, but when? 2004 or 2005?
If it is early 2004, then there is no real problem. Juniper will prosper and their current valuation is not really out of line. If it is late 2004 or 2005 then products from Cisco and a number of other vendors may be mature enough to compete on price/performance causing lower market share and lower margins. Then Juniper will lose its edge, and in this case its current valuation is too high.
Paul.