It seems like people are just looking at the trending hashtags, and spamming, which then gets them into search results. How can twitter solve this? Any ideas?

For example, I did a search for #media140 which is an event in London today. The whole page of results was all spam tweets from the same account, with popular search terms and hashtags in it, (And an affiliate/target link).

eg http://twitter.com/Janet104807/statuses/1859946423

also http://search.twitter.com/search?max_id=1859950510&page=1&q=www.goldencasinoflash.com

Another point is this spam would artificially increase the "trending topics" - feedback loop.

It seems like the search functionality could become useless pretty quickly if spamming isn't stopped in its tracks. It'd be very easy to write an app to create twitter accounts, find trending hashtags, popular keywords, then start sending out tweets with affiliate links. Go through web proxies to avoid any banning by IP. Do they already exist?

Google solved this for website search with PageRank, and other algorithms to detect spam, how could twitter do a similar thing?

Thoughts?