A needs line of effect to every space into which a spell will create an effect

O Manual do Jogador on Line of Effect, in part, says, "You must have a clear line of effect… to any space in which you wish to create an effect" (176). Further, on Efeito diz

You must designate the location where these things are to appear, either by seeing it or defining it (for example, "The insect plague [effect] will appear 20 feet into the area of darkness that the nagas are hiding in"). Range determines how far away an effect can appear, but if the effect is mobile (a summoned monster, for instance), it can move regardless of the spell’s range." (175 and link mine)

Further, special rules apply to effects brought forth by spells of the magic school conjuração:

A creature or object brought into being or transported to your location by a conjuration spell cannot appear inside another creature or object, nor can it appear floating in an empty space. It must arrive in an open location on a surface capable of supporting it. (172)

(It's a mystery to this reader why the printed text presents this information in exactly the oposto order that the reader needs it!)

A spell of the subschool convocação typically creates an effect, so the caster needs line of effect to the entire space into which the summoned creature or object will appear. Likewise, a caster needs line of effect to the entire space where a wall spell—like the 6th-level Sor/Wiz spell parede de ferro [conj] (PH 299)—will see its effect created. Finally, a caster needs line of effect to the entire space where a sphere spell—like the 4th-level Sor/Wiz spell Otiluke's esfera resiliente [evoc] (PH 258)—will see its effect created.

Finalmente, o Manual do Jogador on Line of Effect also says, "An otherwise solid barrier with a hole of at least 1 square foot through it does not block a spell's line of effect" (176). A 6-ft. diameter pillar occupies the square it's in and some of the surrounding squares, so it's a barrier and would prevent the creation of effect spells in that the square it wholly occupies. However, in the surrounding squares—into which the pillar's diameter extends only 6" or so—there is much more than a square foot into which to put stuff, and it wouldn't block line of effect. (By the way, a pilar in D&D 3.5 is usually either delgado—not occupying a square therefore not a barrier—or Largo—occupying a square therefore a barrier.)

O problema com esfera prismática et ai.

Some sphere spells—like the 9th-level Sor/Wiz spell esfera prismática [abjur] (PH 264)—are given Efeito entries the DM should probably modify these spells.

That is, when such a spell tries to create an effect that's a sphere around a creature and that sphere effect would extend beyond the creature, such a sphere spell deveria create an effect that's a dome sobre a creature that's on a surface, the remainder of the spell's effect occluded by the surface. However, a spell that creates an effect that's a big enough sphere—like the esfera prismática spell's 10-ft.-radius one—means that unless the caster somehow has line of effect to the space abaixo the target the spell should, instead, tecnicamente fail as the caster doesn't have clear line of effect to those spaces because those spaces themselves aren't clear.

O Manual do Jogador diz Spell Failure

If you ever try to cast a spell in conditions where the characteristics of the spell (range, area, or the like) cannot be made to conform, the casting fails and the spell is wasted. (171)

And a spell like esfera prismática doesn't allow any choices when its effect is created. For example, the spell parede de ferro tem Effect: Iron wall whose area is up to one 5-ft. square/level, Mas uma esfera prismática feitiço tem Effect: 10-ft.-radius sphere centered on you, without an até and without any concessions for creating an effect at anything less than its maximum—and only—size.

In sum, by a strict reading, such a spell can affect apenas a creature that's flying, swimming, and the like. To avoid pointlessly penalizing such spells and having archmages looking like nitwits because they forgot this technicality, this DM recommends changing such spells on a case-by-case basis when appropriate, and, as always, the DM first informing players of this change.

The general rule (described in "Line of Effect" under "Aiming a Spell") is that line of effect from the caster is required to create an effect in a square. There is an exception (in the "Area" section) for bursts, spreads, and emanations: they require line of effect from the caster to the point of origin and from the point of origin to any affected square (but not necessarily from the caster to the square).

The first two examples in the question (summoning a creature and creating a wall) fall under the general case, and require line of effect from the caster to all affected squares. The final example (a spherical burst) falls under the specific exception, and requires line of effect from the point of origin to all affected squares (Prismatic Sphere in particular calls out in its description that half of the sphere will generally not be created due to the caster standing on a solid surface).

That said, in my personal experience, it's a quite common house rule to extend the special rules for bursts, emanations, and spreads to all spells. In these cases, the point of origin is generally either the center or an edge of the effect. I've not found this to be disruptive to any game I've played in, and have found that, subjectively, it improves enjoyment of the game more than it detracts from it.