Might be a little much, but I got curious and looked up difference in requirements between FBS and FCS on the NCAA website and found this...
FBS (Formerly Division I-A) Standards
Number of Varsity Sports including football: 16 (7-8 mens/ 8-9 womens)
Attendance Requirements: Average minimum 15,000 paid or actual attendance
Scheduling: 60% FBS opponents, minimum 4 home games against FBS opponents
Scholarship Limit: 85
I also remember reading that schools in FBS are required to have a minimum athletic budget and their stadiums must hold a minimum of 30,000 people, but I didn't see those listed on the site.
FCS (Formerly Division I-AA) Standards
Number of Varsity Sports including football: 14 (7/7 or 6/8)
Attendance Requirements: None
Scheduling: 50% against either FCS or FBS opponents
Scholarship Limit: 63
As for the teams: Lamar will take the field in 2010, UTSA in 2011, both as members of the Southland Conference (FCS)
UTA has had discussions, but nothing more
I knew Texas State had been working toward moving up to FBS for awhile, but Stephen F. Austin is surprising
And just to throw it in there, UT-Tyler is looking to add football, albeit on a Division III level.