Many of the ground personel have been called back to work (CSRs, rampers, aircraft cleaners) at the Hubs and UAL has been hiring off the street for those type of positions for about 2 months now. Also all non-voluntary FA furloughlees have been recalled leaving about 600 voluntary FAs that have not returned to work.
Those jobs you have seen will be offered to any other furloughees that are interested, including pilots. I know of a couple that have been hired as CSRs. The positions are advertised first on a private employee/furloughee website and if they are not filled by those people United then advertises for them on their website and newspapers. So you have nothing to lose by applying if you are interested since those jobs have already been offered to employees/furloughees and no one took them. Good Luck.