Intel is trying to expand their lower end lineup of processors to compete with AMD's.
It's not actually a Celeron like the original Celerons you're thinking of (Netburst architecture). It's still based off the Core 2 architecture, just a really stripped down version. The core is Allendale I think, although it only has 512KB of cache.
They're not terrible processors, but the tiny cache hurts them. Same with the new Pentium lineup (E21XX line), although they have 1 MB cache. The E4XXX series is much better, with 2 MB of cache.