Intel is planning on beefing up Celeron-D quite soon, once they begin rolling out with the 65nm line. Aside from an increase in clockspeed to 3.20 and 3.33GHz, the Celeron D 352 and 356 will also feature a much larger L2 cache (512kb), 64bit extensions (as current celerons do) and most importantly, a faster FSB, bringing the Celeron up to 800 and possible 1066MHz FSB. Essentially, this is turning the Celeron into a beast that far exceeds the Northwood P4 line, which is the most common midrange P4 line in use. As a "budget" processor, the Celeron has been popular over the years because it is typically a low priced, highly-overclockable CPU that is useful for both cheap PCs and enthusiasts on a budget.
Competing currently with Sempron, existing Celerons up to 2.66GHz really don't match up, but perhaps these revisions will make it a serious contender. Depending on the price, it may be a way to go, especially if it works in 945/955 chipset motherboards, allowing a future upgrade path to P4.