Great spot Governator. Checked last 3 years as well:
Teams in playoff position as of April 30 2014: NYY, OAK, DET, TEX, KCR and MIL, ATL, SFG, NYM, WSH. Of these 4/5 made it from the AL and 2/5 from NL so 60% success rate.
Teams in playoff position as of April 30 2013: BOS, TEX, BAL, NYY, DET and ATL, COL, STL, PIT, SFG. Of these 2/5 made it from the AL and 3/5 from NL so 50% success rate.
Teams in playoff position as of April 30 2012: TEX, TB, BAL, NYY, CLE and LAD, WSH, STL, ATL, NYM. Of these 3/5 made it from the AL and 3/5 from NL so 60% success rate.
Edit: I should also point out that the last 3 world series champions (2013-2015) were in playoff positions as of April 30 as well.