Billionaire investor Carl Icahn has made a $50 million investment in mobile phone content provider Motricity, the second investment made by the financier in recent weeks in firms with strengths in mobile wireless.

The Motricity investment appeared to be on friendly terms as the Tuesday announcement was made by the firm, which noted that Icahn's son, Brett Icahn, would join Motricity's board of directors. On Jan. 30, Motorola reported that the senior Icahn had made a major investment in that firm.

Motricity provides a variety of content to mobile phone service providers including AT&T's Cingular Wireless, Alltel, and Sprint, as well as to media and entertainment companies including NBC, Turner, and Warner Music Group.

Motricity's Fuel 5 platform has a range of sectors that deliver messaging and content including ringtones, games, applications, graphics, and music to mobile subscribers.

In a statement, Carl Icahn said Motricity is "well-positioned for dominance in mobile content, a sector for which we forecast growth in the coming years."