The body of work following the decision in Fifield v. Premier Dealer Services is somewhat scattered at best. Federal courts are divided on whether it represents the law in Illinois, with courts taking divergent views.
As most readers may know by now, Fifield stands for the proposition that a covenant not to compete signed by an at-will employee requires at least two years of continued employment for that to constitute sufficient consideration. The key aspect of Fifield is that this consideration rule applies even when an employee signs a covenant at the start of employment, rather than during the course of employment. An undecided issue is how Fifield applies to lawsuits outside Illinois' First District (that is, Chicago).
The Seventh Circuit, though, is primed to weigh in. The plaintiff in Instant Technology LLC v. DiFazio has appealed its loss to the circuit court, and one of the central features of the district court's holding was that Fifield barred the non-compete claims. The district court judge discussed Fifield at length in his memorandum opinion. My discussion of the district court ruling is here.
The plaintiff in Instant Technology is due to file its appellate brief in a few weeks. I will look forward to reading how much it attacks the reasoning from Fifield and whether the two-year rule is likely to be a central feature of the appeal.