I'm no longer the parted maintainer, re-assigning.
Reproduced on RHEl 6.1 in KVM guest. Tested on latest 6.2 nightly:
# rpm -q parted
# parted /dev/vdb -s mkpart primary 0 1GB
Warning: The resulting partition is not properly aligned for best performance.
# parted /dev/vdb -s print
Model: Virtio Block Device (virtblk)
Disk /dev/vdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number Start End Size Type File system Flags
1 512B 1000MB 1000MB primary
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.