101 Billboards: The New Ad Unit?

Driving up 101 North last night, we passed billboards advertisements for: - eBay (several billboards featuring their new ad campaign) - Zazzle (see below, clearly in time for the holiday gift giving season) - Zynga (which was simply a red sign with their white dog - not text whatsoever) - Droid (featuring the handset and prominent Verizon / Google logos) - Yahoo (a pink billboard featuring their new ad campaign)

When did advertising on 101 become so fashionable? I understand that Droid advertisement (it is time sensitive and a consumer product play) but since 2003, I have not seen such a flurry of branding-based billboard ads... Perhaps the prices have plummeted!