First, as pointed out by Reading Ram in this fanpost, rumors have surfaced that McNabb will be a Ram by Friday. The report at Rotoworld, expressing considerable disbelief, says that it would be for the Rams first pick of the second round. That's where I tend to get skeptical of this rumor.
That's a valuable piece of real estate for the Rams in this draft. If they keep it, they can get a real quality player, or they could trade it for maximum value (like more picks) when teams break for the night after the first round of the draft. A team that's been making every effort to bring in young talent surely wouldn't surrender one of their most valuable picks for a 33-year-old QB who has played 16 games just once in the last six years. If they opt to pass on a QB with their first round pick, they'd be likely to bring in a free agent, lower valued trade or bring back Bulger. Then there's this from the Rotoworld report:
For the Rams to part with a high pick, they'd need McNabb to agree to an extension. It's likely that the 33-year-old would balk at a long-term deal with a team so far removed from playoff contention.
Whether you'd like to see McNabb in a Rams uni or not, this just wouldn't be a sound move for the team.
Of course, maybe there's nothing to it as a later report says that the Eagles are refusing offers for McNabb.