It is possible but how depends on what you are trying to accomplish. If it's this:
| Left-aligned Right-aligned | in one cell then you can use floating divs inside the td tag:
|
Left-aligned
Right-aligned
|
If it's
| Left-aligned
Right Aligned |
Then Balon's solution is correct.
If it's:
| Left-aligned | Right-Aligned |
Then it's:
| Left-aligned |
Right-Aligned |