Here, hCG stands for "human Celera Genome". hCG-prefixed protein and gene descriptors are used as a last resort for genes which are found only in Celera's database.
See for example http://www.ncbi.nlm.nih.gov/protein/119619226 , the gene you referred to as "hCG1809003". As the entry says, this was submitted by Celera in 2005 as a putative gene, after being found by "conceptual translation", that is, scanning the Genome Project data for start and stop codons. It is likely this gene has yet to be found as RNA or protein - because the only references for that gene are Celera's submission and the Genome Project paper. Nevertheless, Celera's sequencing (and microarray!) software and chips still look for it.
Your two example genes eventually made it to GenBank. The first example even has a proper name and function assigned - sulfatase 1. Many genes remain in hCG limbo.