I think SeaMicro is targeting commercial workloads, not HPC; that immediately excludes GPUs as competitors. It could be somewhat cheaper and lower power than a Nehalem cluster, but I also don't see anything revolutionary.<p>Their patent applications have some technical details:
<a href="http://www.pat2pdf.org/pat2pdf/foo.pl?number=20080320181" rel="nofollow">http://www.pat2pdf.org/pat2pdf/foo.pl?number=20080320181</a>
<a href="http://www.pat2pdf.org/pat2pdf/foo.pl?number=20090216920" rel="nofollow">http://www.pat2pdf.org/pat2pdf/foo.pl?number=20090216920</a> It looks kinda like a cheap x86 Blue Gene...