A long/short option rollout is a term swap on the option. I think it's easiest to see it by example, so we'll use one of the trades I've employed recently.
This would be an example of a short option rollout. I had 30 WM April '08 calls @ 11 covered. Since the stock was trading over $11 the week of the option expiration, I "rolled out" of the April '08 calls into the May '08 calls. When you do this, you are simply exchanging time value for the risk of being exercised. So, I simultaneously bought to cover the 30 WM April '08 calls and shorted the May '08 calls @ 11 which results in a small time-value profit from the difference in premiums.
A long option rollout would be the exchange of two long option positions for the cost difference in time value (the opposite trade). A short rollout is typically on the credit side (makes you money in the premium difference) and a long rollout is typically on the debit side (costs you a little in premium difference).
Each rollout has its own set of advantages and disadvantages. A short rollout is usually employed to "rehabilitate" a stock price. In the case of WM, I'm trying to get my basis in that stock as low as possible in order to absorb its volatility. I do this by taking small premiums from the time-value of short term options. The downside to this strategy is that I run the risk of having my position taken from me at a less-than-optimal price, and I can't participate in the strong 20%-30% upswings that happen occasionally.
By constrast, long option rollouts have the decided advantage of letting you select your profit-taking opportunity for a very low capital commitment. Also, by rolling the calls, you absorb much of the cost of letting out-of-the-money options expire and subsequently having to purchase back into the same position.
Hope this clears it up for you and that I haven't just muddied the waters.