Matticus also has a guest blogger on his site (I posted about Phaelia's guest blogger earlier today), and he's got a great post up too, about healing meters and why they just aren't helpful to anyone. Damage meters are well known to be disliked by many players -- while they can often show some DPSers where they fit in the general rankings, they're usually still not a great indicator of performance (and when DPS gets really involved in beating the meters, then things go bad quickly).
But healing meters are even worse. Given all of the crazy mechanics in the game (from armor and self-heals to situational abilities and AoE heals), they are very rarely (if ever) a valid interpretation of who's doing the healing and whether they're doing it right or wrong. And as guest blogger Ulkesshern says, more healing doesn't make a better healer anyway -- overhealing and spamming big heals do not mean you're a good healer, though they may get you higher on the healing meters.
There is one good word for healing meters, and that's to give the healer an ego boost after you show off the DPS meters at the end of the instance (usually they're on the bottom of DPS, and so when you switch over to healing, they're happy to be back on top again). But Ulkesshern makes a good point: for anything worth tabulating or tracking, healing meters are not to be trusted or followed.