Why is it important for SEs to use SalesForce.com?
When Salesforce.com (or any other CRM) is your key point for communicating the value of the opportunities and current accounts, it is vital that all relevant data is summarised and available for the sales management to read. Having all the information the deals you are working in your head, your email or just on a spreadsheet is not going to help people realise how your deals are going. Since the job of the SE is to ensure that the technical recommendation (and the business one where possible) is made in your company's favour, it is important that the sales team is aware in general of how the deal is looking.
Of course business is fluid, and there may be times that the status quickly changes, but you should make a point of keeping the opportunity data up to date, and logging any important actions in the system. Often, SEs and their Sales reps are often separated either by miles, timezones and availability, even the main two people on the deal will have to check what the status is, and it may as well be the same place everyone else will look.
Don't be afraid of putting problems or issues that you've discovered here. Your management will look upon these much worse if they turn up right at the time the deal was supposed to be signed, when you are hopefully off snowboarding in Colorado.
Putting templates of your RFP answers, and your regularly sent emails into the system means you can quickly send things out to lots of customers, or find that sizing recommendation that everyone needs.
So train your sales rep to put you in their Sales team, BCC salesforce.com onto any important emails you send out to your customers, and become that key person in the sales team that everyone knows you are.