All you have to do is go to your local county recorder's office and see if either an NOD or NOTS have been recorded. If so, by looking at the recording date, you'll know how soon the property can be foreclosed upon. If neither have been recorded, then the house is not currently in foreclosure.
Of course, just because the house isn't presently in foreclosure, that doesn't mean the owner isn't behind on his/her payments and heading in that direction. To ensure against that possibility, you could always ask the owner to provide a copy of their most recent mortgage statement (allowing them to black out any confidential information) to prove that everything is current. Many landlords, though, would probably balk at that and give you a 'You Gotta Be Kidding' type of response.
You can also try calling the main county office for one of your local title companies. Most of them have customer service departments, which have access to county records and they'll probably be willing to look up whether an NOD or NOTS have been recorded at no charge. The title company can also tell you how much the loan is on the property, which may help you determine whether the owner owes more on the house than it's worth. Keep in mind that just because someone is "upside-down" on their loan doesn't mean that they're a candidate for foreclosure, but someone in that financial position is certainly far more likely to go into foreclosure than an owner who still has plenty of equity.
Finally, you may be interested to know that Fannie Mae just adopted a policy whereby renters of Fannie Mae foreclosed homes will be allowed to stay in the home after foreclosure (until the home is re-sold by Fannie Mae). Up until now, most renters were either enticed to move or evicted right away after foreclosure.
Watch out for the bus!