There’s no question Silicon Valley can be a competitive place to do business. But sometimes, when faced with a common foe or technological challenge, tech companies and developers can be surprisingly cooperative. So it is that we have Google announcing today that it’s working with the blogging community and other search engines to try to combat a relatively new scourge known as comment-spam.

What is comment spam? It’s when spammers leave sometimes innocuous-looking postings in the comments sections of blogs with links to web sites hawking whatever they’re selling (online poker sites seem to be popular these days). Here’s an example or two. The twist is that the links are not intended to be viewed by humans. The spammers put them there hoping search engine crawlers will come by, scoop up the link info and add it to their indexes. The more links the spammers can propagate across the Net, the better their rankings in the search results.

Most blog readers probably never notice the spam — unless their favorite blogger stops accepting comments altogether, inhibiting the free-flowing dialogue that’s supposed to be at the core of blogging. But behind the scenes, many bloggers have been engaged in a tiring arms race to keep the comment spam off their Web sites.

Lately, some bloggers have suggested that Google (and other search engines) should stop indexing links in blog comments. And that’s what Google has sort of decided to do. Google’s announcement coincided with cooperative announcements from other leaders in the blogging and search community, including Yahoo, MSN and Six Apart.

Will it make a difference? We’re somewhat skeptical. Spammers are nothing if not resourceful and determined. And this fix may have unintended consequences. But time will tell. For now, though, tens of thousands of bloggers are rejoicing that the companies put aside their rivalries for the common good.

Now, about collaborating on that other spam problem….