Should businesses blog?

I’m putting together a story about blogging for UK businesses, and I’d be interested in people’s opinions on the subject. Do you think firms – such as online shops, small firms, whatever – should be blogging, or would their time be better spent concentrating on the basics such as price, decent customer service and so on? Have you ever chosen a product based on what bloggers have said about it – or decided against a product because of bad word of mouth among bloggers? Would you trust a firm’s own weblog, or would you assume that everything’s being written under the harsh glare of PR types and control-freak bosses?

Any opinions would be very, very welcome.

PS: as I’m soliciting opinions for a written feature, I’m assuming that anyone who leaves a comment or emails me about this is happy for me to quote them in print. If you’d rather I didn’t, please say so in your comment or email. Thanks.