Officials at eBay have pulled the company's advertising from Google's U.S. network in move that many see as retaliation for Google's attempt to crash eBay's recent Boston conference.

eBay pulled its ads after Google threw a competing party in Boston for the launch of its new online payment service, Google Checkout. While the service clearly competes with eBay's PayPal property, the rival party signaled bad blood between the two companies.

"We've seen that the two companies have been on a collision course for a long time," Derek Brown, an analyst for Cantor Fitzgerald, told the San Francisco Gate. "This seems to be the latest and most bizarre twist."

Hani Durzy, a spokesman for eBay, declined to comment on why the company pulled its ads, but he did say that the company was disappointed by Google's decision to run a competing event during eBay's user conference.

Most recently, the two rivals crossed swords when eBay announced its decision to broker radio ads. Google has its own partnership with Clear Channel to sell radio ads.