  With a sample of approximately 89 million BBbar pairs collected with the
BABAR detector, we measure branching fractions, determine the degree of
longitudinal polarization, and search for direct CP violation in the decays
B0=>phiK*0 and B+=>phiK*+. We perform a search for other charmless
vector-vector B decays involving rho and K*(892) resonances and observe the
decays B+=>rho0K*+ and B+=>rho0rho+. The branching fractions are measured to be
BR(phiK*0)=(11.1^{+1.3}_{-1.2}\pm 1.1)10^{-6},
BR(phiK*+)=(12.1^{+2.1}_{-1.9}\pm 1.5)10^{-6},
BR(rho0K*+)=(7.7^{+2.1}_{-2.0}\pm 1.4)10^{-6}, and
BR(rho0rho+)=(9.9^{+2.6}_{-2.5}\pm 2.5)10^{-6}. The longitudinal polarization
fractions are measured to be GammaL/Gamma(phiK*0)=0.65\pm 0.07\pm 0.04 and
GammaL/Gamma(phiK*+)=0.46\pm 0.12\pm 0.05. We measure the charge asymmetries:
ACP(phiK*0)=+0.04\pm 0.12\pm 0.02 and ACP(phiK*+)=+0.16\pm 0.17\pm 0.04.
