I have been hedging my horticultural bets and planting seeds a bit earlier than usual, which for me is around Mother's Day. On the seed packets I look for disclaimers like "sow after all last possible frost date" and set those aside, planting only those seeds that a little frost will not harm. The Farmer's Almanac predicts that May 1 is the last frost date for Toledo in 2010, and I have seen dates as early as April 25 and as late as May 15 for this year's last killing frost.
However, I suspect that we may have already seen the last of the frost until autumn. It is over 70 degrees again today, and the 10-day forecast shows lows around 40 degrees for the foreseeable future. Since my bulb plants are at least five days ahead of schedule, the forecast looks good for the first seeds I have planted.