Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: About six months ago, I told you to prepare for "a trucking renaissance." Remember? Well, guess what -- it just pulled into the delivery bay. This morning, less-than-truckload weight trucker Old Dominion Freight (Nasdaq: ODFL) hit the gas and gunned its stock price up 10%. Its fuel of choice: an earnings beat.

So what: Citing a massive 21% spike in shipping volume, Old Dominion confirmed that the trucking industry is pulling out of a three-year slump, with the company nearly tripling quarterly profits and delivering $0.38 per share into the pockets of shareholders.

Now what: OD's winning quarter follows similarly strong results out of JB Hunt (Nasdaq: JBHT) this month and came simultaneously with much larger shipper UPS (NYSE: UPS) reporting a "beat" of its own -- two facts that suggest this revival may be as wide as it is deep. On the other hand, rival Arkansas Best (Nasdaq: ABFS) turned in more tepid results Monday.

The big question for trucking speculators remains: Which road will notorious yo-yo stock YRC Worldwide (Nasdaq: YRCW) follow?

Add it to your watchlist , and be first to learn the answer when YRC reports next month.