It looks like retail giant Walmart has made another acquisition. The e-commerce giant has bought Social Calendar, an app on Facebook that allows you to get birthday and holiday reminders by email and SMS, and to post personalized photo cards and other virtual greetings on friends’ Facebook Walls on their birthdays.

Here’s the message posted on Social Calendar’s site: Wal-Mart Stores, Inc. (“Walmart”) completed its purchase of Newput Corporation’s Social Calendar products, services and website. We remain committed to providing the highest level of service that you have come to expect with Social Calendar. Your service with Social Calendar will continue without any interruptions, and you will be notified in the future of any material updates or changes to your service.

As we’ve written in the past, SocialCalendar, which was founded by Raj Lalwani and David Jordan, lets you plan events among Facebook friends, get movie showtimes and integrate events into a public calendar. Users can also import and get email reminders about events, birthdays and anniversaries and lets users buy virtual good icons as presents for friends and to mark events on calendars.

In 2009, the company debuted a partnership with Hallmark cards (Hallmark also invested in Social Calendar), to allow users to send virtual cards and gifts as well. The app has 15 million installed users and around 400,000 monthly active users. Social Calendar cites 110 million+ birthdays, holidays, other special occasions added by users and sends 10 million email reminders each month.

It should be interesting to see what Walmart does with Social Calendar. The company recently launched Facebook app Shopycat, which suggests gifts based on social profile of a friend. We know that Shopycat will function as an online store itself on Facebook, allowing users to buy from Walmart without every having to leave the social network. Social Calendar’s technology could be integrated into this app.

Walmart has been on an e-commerce tear, acquiring technologies and companies that can help add personalization, mobile, social media and other functionality to the buying process. Over the past year, Walmart has acquired social media technology provider Kosmix, Small Society, and OneRiot. The company also recently invested in Yihaodian, a massive B2C eCommerce company based in China.