Google Now also shows cards for "breaking news and other developing stories you may be interested in", based on your web history.
It's not clear if the new updates feature will replace the reminders feature. Right now, a search for [U2] shows "Remind you about new releases", while a search for [Madonna] shows "Get updates about Madonna".
"Keeping up with the latest information about your favorite musicians, movie stars and other notable people just got easier thanks to the Knowledge Graph and Google Now," informs Google. "Say that you're a Lady Gaga fan and like staying informed about her latest album releases. On the Google Search App, search for [lady gaga]. On the card that pops up, tap 'Remind you about new releases?' and Google Now will keep you updated on your phone or tablet. Similarly, use Google Now to stay in the know about your favorite athletes. For example, search for [colin kaepernick] and tap 'Get updates about Colin Kaepernick' on his card; doing so lets Google Now know that you'd like to receive news. Remember that to use this feature, you'll need to be signed into your Google account on the Google Search App."
Well, I don't see 'Remind you about new releases?' when searching for [Lady Gaga].